add: scrapeConfigSelector check

[nidhey27]

Description

The current Prometheus Operator implementation checks for the presence of spec.serviceMonitorSelector, spec.podMonitorSelector, and spec.probeSelector to determine if the Prometheus configuration should be treated as unmanaged. However, the documentation specifies that the operator should also check for spec.scrapeConfigSelector. This PR aligns the implementation with the documentation by adding the necessary check for spec.scrapeConfigSelector.

Closes #5928

Type of change

What type of changes does your code introduce to the Prometheus operator? Put an x in the box that apply.

• CHANGE (fix or feature that would cause existing functionality to not work as expected)
• FEATURE (non-breaking change which adds functionality)
• BUGFIX (non-breaking change which fixes an issue)
• ENHANCEMENT (non-breaking change which improves existing functionality)
• NONE (if none of the other choices apply. Example, tooling, build system, CI, docs, etc.)

Changelog entry

Ensure that the operator checks for spec.scrapeConfigSelector when determining if the Prometheus configuration should be treated as unmanaged.

[simonpasquier]

Thanks!