Test PGSM with multiple extensions loaded in the server.

[Naeem-Akhter]

Added a tap test case to load multiple extensions in the server before running a test load.

1. We load and create other extensions that are distributed by Percona. (postgis, pg_repack, pgaudit, pgaudit_set_user, pgpool)
2. Run test data with pgbench.
3. Make sure there is no segmentation fault or server crash.

To make the above test case work, updated the workflows to install above mentioned extension where we use installed packages from PPG or PGDG. On workflows where we build server from source, we are skipping this test case.

Also removed the workflows for postgres 11, as it is already EOL.

[codecov[bot]]

Codecov Report

Merging #428 (9c7b163) into main (823bfb9) will not change coverage. Report is 3 commits behind head on main. The diff coverage is n/a.

@@           Coverage Diff           @@
##             main     #428   +/-   ##
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  Coverage   90.70%   90.70%           
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  Files           3        3           
  Lines        1270     1270           
  Branches       35       35           
=======================================
  Hits         1152     1152           
  Misses         96       96           
  Partials       22       22           

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