Add observability tests

[Zvirovyi]

Add tests to check main service logs presence (postgresql, patroni, pgbackrest).

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 80.96%. Comparing base (0f2c8c2) to head (4d2222b).
Report is 7 commits behind head on main.

❗ Current head 4d2222b differs from pull request most recent head 76437bc. Consider uploading reports for the commit 76437bc to get more accurate results

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #401      +/-   ##
==========================================
+ Coverage   80.31%   80.96%   +0.65%     
==========================================
  Files          10       10              
  Lines        2301     2259      -42     
  Branches      376      363      -13     
==========================================
- Hits         1848     1829      -19     
+ Misses        369      354      -15     
+ Partials       84       76       -8     

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