PG16 - Add reindex database/system tests (#7167)

In PG16, REINDEX DATABASE/SYSTEM name is optional.
We already don't propagate these commands automatically.
Testing here with run_command_on_workers.

Relevant PG commit:
https://github.com/postgres/postgres/commit/2cbc3c1

src/test/regress/expected/pg16.out

@@ -654,6 +654,28 @@ SELECT pg_get_viewdef('pg16.prop_view_1', true);
 
 \c - - - :master_port
 SET search_path TO pg16;
+-- REINDEX DATABASE/SYSTEM name is optional
+-- We already don't propagate these commands automatically
+-- Testing here with run_command_on_workers
+-- Relevant PG commit: https://github.com/postgres/postgres/commit/2cbc3c1
+REINDEX DATABASE;
+SELECT result FROM run_command_on_workers
+($$REINDEX DATABASE$$);
+ result
+---------------------------------------------------------------------
+ REINDEX
+ REINDEX
+(2 rows)
+
+REINDEX SYSTEM;
+SELECT result FROM run_command_on_workers
+($$REINDEX SYSTEM$$);
+ result
+---------------------------------------------------------------------
+ REINDEX
+ REINDEX
+(2 rows)
+
 \set VERBOSITY terse
 SET client_min_messages TO ERROR;
 DROP SCHEMA pg16 CASCADE;

src/test/regress/sql/pg16.sql

@@ -375,6 +375,19 @@ SELECT pg_get_viewdef('pg16.prop_view_1', true);
 \c - - - :master_port
 SET search_path TO pg16;
 
+-- REINDEX DATABASE/SYSTEM name is optional
+-- We already don't propagate these commands automatically
+-- Testing here with run_command_on_workers
+-- Relevant PG commit: https://github.com/postgres/postgres/commit/2cbc3c1
+
+REINDEX DATABASE;
+SELECT result FROM run_command_on_workers
+($$REINDEX DATABASE$$);
+
+REINDEX SYSTEM;
+SELECT result FROM run_command_on_workers
+($$REINDEX SYSTEM$$);
+
 \set VERBOSITY terse
 SET client_min_messages TO ERROR;
 DROP SCHEMA pg16 CASCADE;