[SDTEST-740] Minor telemetry fixes

[anmarchenko]

What does this PR do?

• Sends code_coverage_is_empty telemetry metric only when code coverage is empty and test was not skipped
• Adds additional unit tests for skipped tests metric

How to test the change? Unit tests are provided

[codecov-commenter]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Project coverage is 98.93%. Comparing base (1da7397) to head (c82db0d).

Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #226 +/- ## ======================================= Coverage 98.93% 98.93% ======================================= Files 262 262 Lines 12440 12461 +21 Branches 560 560 ======================================= + Hits 12307 12328 +21 Misses 133 133 ```

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