Artem Gavrilov

@codeforall Please check last commit. It restores/fixed previous behavior for PG less than 17 because nesting level fix should not be back-ported (similar to pg_stat_statements). `level_tracking_1.out` result matches to `level_tracking`...

According to https://www.postgresql.org/developer/beta/ first PG 17 beta will be available in May 2024.

Ticket for updating PMM Dashborads: https://perconadev.atlassian.net/browse/PMM-13154