Make ReportRemoteError's CONTEXT style-compliant

There's not a ton of documentation about what CONTEXT lines should look
like, but this seems like the most dominant pattern. Similarly, users
should expect lowercase, non-period strings.

src/backend/distributed/utils/connection_cache.c

@@ -298,7 +298,7 @@ ReportRemoteError(PGconn *connection, PGresult *result, bool raiseError)
 							 messageDetail ? errdetail("%s", messageDetail) : 0,
 							 messageHint ? errhint("%s", messageHint) : 0,
 							 messageContext ? errcontext("%s", messageContext) : 0,
-							 errcontext("Error occurred on remote connection to %s:%s.",
+							 errcontext("while executing command on %s:%s",
 										nodeName, nodePort)));
 	}
 }

src/test/regress/expected/multi_index_statements.out

@@ -141,11 +141,11 @@ ERROR:  relation "lineitem_orderkey_index" already exists
 CREATE INDEX try_index ON lineitem USING gist (l_orderkey);
 WARNING:  data type bigint has no default operator class for access method "gist"
 HINT:  You must specify an operator class for the index or define a default operator class for the data type.
-CONTEXT:  Error occurred on remote connection to localhost:57638.
+CONTEXT:  while executing command on localhost:57638
 ERROR:  could not execute DDL command on worker node shards
 CREATE INDEX try_index ON lineitem (non_existent_column);
 WARNING:  column "non_existent_column" does not exist
-CONTEXT:  Error occurred on remote connection to localhost:57638.
+CONTEXT:  while executing command on localhost:57638
 ERROR:  could not execute DDL command on worker node shards
 CREATE INDEX ON lineitem (l_orderkey);
 ERROR:  creating index without a name on a distributed table is currently unsupported

src/test/regress/expected/multi_modifications.out

@@ -151,12 +151,12 @@ INSERT INTO limit_orders VALUES (18811, 'BUD', 14962, '2014-04-05 08:32:16', 'se
 								 -5.00);
 ERROR:  new row for relation "limit_orders_750000" violates check constraint "limit_orders_limit_price_check"
 DETAIL:  Failing row contains (18811, BUD, 14962, 2014-04-05 08:32:16, sell, -5.00).
-CONTEXT:  Error occurred on remote connection to localhost:57637.
+CONTEXT:  while executing command on localhost:57637
 -- INSERT violating primary key constraint
 INSERT INTO limit_orders VALUES (32743, 'LUV', 5994, '2001-04-16 03:37:28', 'buy', 0.58);
 ERROR:  duplicate key value violates unique constraint "limit_orders_pkey_750001"
 DETAIL:  Key (id)=(32743) already exists.
-CONTEXT:  Error occurred on remote connection to localhost:57638.
+CONTEXT:  while executing command on localhost:57638
 SET client_min_messages TO DEFAULT;
 -- commands with non-constant partition values are unsupported
 INSERT INTO limit_orders VALUES (random() * 100, 'ORCL', 152, '2011-08-25 11:50:45',
@@ -270,7 +270,7 @@ INSERT INTO limit_orders VALUES (275, 'ADR', 140, '2007-07-02 16:32:15', 'sell',
 INSERT INTO limit_orders VALUES (275, 'ADR', 140, '2007-07-02 16:32:15', 'sell', 43.67);
 ERROR:  duplicate key value violates unique constraint "limit_orders_pkey_750001"
 DETAIL:  Key (id)=(275) already exists.
-CONTEXT:  Error occurred on remote connection to localhost:57638.
+CONTEXT:  while executing command on localhost:57638
 -- Test that shards which miss a modification are marked unhealthy
 -- First: Connect to the second worker node
 \c - - - :worker_2_port
@@ -281,7 +281,7 @@ DROP TABLE limit_orders_750000;
 -- Fourth: Perform an INSERT on the remaining node
 INSERT INTO limit_orders VALUES (276, 'ADR', 140, '2007-07-02 16:32:15', 'sell', 43.67);
 WARNING:  relation "limit_orders_750000" does not exist
-CONTEXT:  Error occurred on remote connection to localhost:57638.
+CONTEXT:  while executing command on localhost:57638
 -- Last: Verify the insert worked but the deleted placement is now unhealthy
 SELECT count(*) FROM limit_orders WHERE id = 276;
  count 

src/test/regress/output/multi_alter_table_statements.source

@@ -262,7 +262,7 @@ NOTICE:  relation "non_existent_table" does not exist, skipping
 ALTER TABLE IF EXISTS lineitem_alter ALTER COLUMN int_column2 SET DATA TYPE INTEGER;
 ALTER TABLE lineitem_alter DROP COLUMN non_existent_column;
 WARNING:  column "non_existent_column" of relation "lineitem_alter_220000" does not exist
-CONTEXT:  Error occurred on remote connection to localhost:57638.
+CONTEXT:  while executing command on localhost:57638
 ERROR:  could not execute DDL command on worker node shards
 ALTER TABLE lineitem_alter DROP COLUMN IF EXISTS non_existent_column;
 NOTICE:  column "non_existent_column" of relation "lineitem_alter" does not exist, skipping
@@ -362,15 +362,15 @@ DETAIL:  Only ADD|DROP COLUMN, SET|DROP NOT NULL, SET|DROP DEFAULT and TYPE subc
 -- types
 ALTER TABLE lineitem_alter ADD COLUMN new_column non_existent_type;
 WARNING:  type "non_existent_type" does not exist
-CONTEXT:  Error occurred on remote connection to localhost:57638.
+CONTEXT:  while executing command on localhost:57638
 ERROR:  could not execute DDL command on worker node shards
 ALTER TABLE lineitem_alter ALTER COLUMN null_column SET NOT NULL;
 WARNING:  column "null_column" contains null values
-CONTEXT:  Error occurred on remote connection to localhost:57638.
+CONTEXT:  while executing command on localhost:57638
 ERROR:  could not execute DDL command on worker node shards
 ALTER TABLE lineitem_alter ALTER COLUMN l_partkey SET DEFAULT 'a';
 WARNING:  invalid input syntax for integer: "a"
-CONTEXT:  Error occurred on remote connection to localhost:57638.
+CONTEXT:  while executing command on localhost:57638
 ERROR:  could not execute DDL command on worker node shards
 -- Verify that we error out on statements involving RENAME
 ALTER TABLE lineitem_alter RENAME TO lineitem_renamed;

src/test/regress/output/multi_copy.source

@@ -456,7 +456,7 @@ COPY customer_worker_copy_append FROM '@abs_srcdir@/data/customer.2.data' with (
 -- Test if there is no relation to copy data with the worker copy
 COPY lineitem_copy_none FROM '@abs_srcdir@/data/lineitem.1.data' with (delimiter '|', master_host 'localhost', master_port 57636);
 WARNING:  relation "lineitem_copy_none" does not exist
-CONTEXT:  Error occurred on remote connection to localhost:57636.
+CONTEXT:  while executing command on localhost:57636
 ERROR:  could not run copy from the worker node
 -- Connect back to the master node
 \c - - - 57636