chore: add instrumentation tests

[mat-rumian]

PR adds tests for instrumentation applied by OpenTelemetry-Operator.

Checklist

• Changelog updated or skip changelog label added
• Documentation updated
• Template tests added for new features
• Integration tests added or modified for major features

[swiatekm]

Overall this looks good to me, thanks for doing it!

One thing I'm wondering is if we shouldn't have self-contained tests per-instrumentation. Right now, you have one feature per instrumented application, and then a single feature that triggers all of them via curl and then checks if the data arrived. It would be more composable if each per-app feature also included the curl trigger and the check. Then it'd be possible to run them individually, and easier to keep track of what data we expect the instrumentation to output.

But that can be done in a followup, if need be. I'll leave it up to you, I'm fine merging this PR as is.