feat: Unit test for otelcol logs assertion

[MichaelThamm]

Issue

Continuation on this PR:

• feat: Check otelcol logs in COS tests #170

Improve the regex with this one.

Solution

Add a unit test to assert that the regex is correctly parsing the otelcol logs.

You can run the unit tests with:

1. just unit -> runs all pytest and TF unit tests
2. just unit-pytest runs all pytest unit tests
3. just unit-tf cos|cos-lite|cos-dev runs the TF unit tests for that specific module

Checklist

• I have added or updated relevant documentation.
• PR title makes an appropriate release note and follows conventional commits syntax.
• Merge target is the correct branch, and relevant tandem backport PRs opened.

[sinapah]

Looks good, but I think the unit test is not being triggered? Should we change the workflow YAML file to run the just recipe for this unit test?