Add optional flags to provides endpoints for PG16 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.

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 70.53%. Comparing base (1d2db72) to head (f807f94).
⚠️ Report is 2 commits behind head on 16/edge.

Additional details and impacted files

@@           Coverage Diff            @@
##           16/edge    #1435   +/-   ##
========================================
  Coverage    70.53%   70.53%           
========================================
  Files           15       15           
  Lines         4259     4259           
  Branches       690      690           
========================================
  Hits          3004     3004           
  Misses        1046     1046           
  Partials       209      209           

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