Re run the crashing test & update the output

src/test/regress/expected/remove_coordinator.out

@@ -14,5 +14,31 @@ BEGIN;
   -- that should fail because of bad hostname & port
   SELECT citus_add_node('200.200.200.200', 1, 200);
 ERROR:  connection to the remote node postgres@200.200.200.200:1 failed
-SSL SYSCALL error: EOF detected
+  -- Since above command failed, now Postgres will need to revert the
-connection to server was lost
+  -- application_name change made in this transaction and this will
+  -- happen within abort-transaction callback, so we won't be in a
+  -- transaction block while Postgres does that.
+  --
+  -- And when the application_name changes, Citus tries to re-assign
+  -- the global pid but it does so only for Citus internal backends,
+  -- and doing so for Citus internal backends doesn't require being
+  -- in a transaction block and is safe.
+  --
+  -- However, for the client external backends (like us here), Citus
+  -- doesn't re-assign the global pid because it's not safe to do so
+  -- outside of a transaction block. This is because, it would require
+  -- performing a catalog access to retrive the local node id when the
+  -- cached local node is invalidated like what just happened here
+  -- because of the failed citus_add_node() call made above.
+  --
+  -- So by failing here (rather than crashing), we ensure this behavior.
+ROLLBACK;
+RESET client_min_messages;
+RESET citus.node_connection_timeout;
+-- restore coordinator for the rest of the tests
+SELECT citus_set_coordinator_host('localhost', :master_port);
+ citus_set_coordinator_host
+---------------------------------------------------------------------
+
+(1 row)
+