Fix Isolation Test Failure in isolation_multiuser_locking in PG17

[m3hm3t]

This PR enhances isolation_multiuser_locking.spec test compatibility across multiple PostgreSQL versions by handling differences in error messages and behavior. Key updates include:

• Error Message Handling: Adjustments to manage version-specific error messages, ensuring consistent test results.

• Modified to address variations in locking behavior across PostgreSQL versions, ensuring test stability in multiuser scenarios.

• REINDEX Behavior Adjustment: This PR accounts for a behavioral change introduced in PostgreSQL by commit ecb0fd337, which alters how REINDEX interacts with system catalogs.

https://git.postgresql.org/gitweb/?p=postgresql.git;a=commitdiff;h=ecb0fd337

[codecov[bot]]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Project coverage is 89.61%. Comparing base (b29c332) to head (94bbb2e).

Additional details and impacted files

```diff @@ Coverage Diff @@ ## naisila/pg17_support #7714 +/- ## ===================================================== Coverage 89.61% 89.61% ===================================================== Files 274 274 Lines 59689 59689 Branches 7446 7446 ===================================================== + Hits 53490 53493 +3 + Misses 4069 4066 -3 Partials 2130 2130 ```