Summary:
Recent commit 015429f added this test. This test fails for release builds, as they consider read committed isolation level as repeatable read. This is set using  `yb_enable_read_committed_isolation` gflag. The fix forces this flag to be true.
Jira: DB-18464

Test Plan: ./yb_build.sh release --cxx-test pgwrapper_pg_backends-test --gtest_filter PgBackendsTest.VerifyResetRetryCounts

Reviewers: asaha

Reviewed By: asaha

Subscribers: yql

Differential Revision: https://phorge.dev.yugabyte.com/D47098