feat: Generic COS assertions function

[MichaelThamm]

Issue

We have many tests doing the same assertions.

Solution

In attempt to be more DRY I added a generic_assertions free function that accepts the correct args to execute all the assertions agnostic to the product flavors:

• COS
• COS Lite
• COS Dev

Any assertions that are specific to a flavor should remain free and called in relevant tests e.g., no_errors_in_otelcol_logs because COS Lite has no otelcol app.

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.

Context

Testing Instructions

Upgrade Notes

[lucabello]

LGTM!