Add optional flags to provides endpoints for PG14 VM

[taurus-forever]

Issue

SolQA is experiencing troubles with automated testing due lack of optional flag for PG interfaces.

Solution

Let's add this flag for cos-agent, as PG can work without COS.
Also, we can consider to add them for legacy interface.... as PG will work (not going to blocked state) when postgresql_client interface is related only. So, legacy interfaces are optionally in fact... Thoughts?!?

Checklist

• I have added or updated any relevant documentation.
• I have cleaned any remaining cloud resources from my accounts.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 75.83%. Comparing base (bf6ecf3) to head (a7c2a09).
⚠️ Report is 6 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #1436   +/-   ##
=======================================
  Coverage   75.83%   75.83%           
=======================================
  Files          17       17           
  Lines        4428     4428           
  Branches      675      675           
=======================================
  Hits         3358     3358           
  Misses        837      837           
  Partials      233      233           

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[marceloneppel]

IMO, putting db and db-admin as optional reinforces the need for moving to the modern relation.