[WIP] feat: Support service names for individual Prometheus Instances

[nidhey27]

Description

This PR introduces the capability for each Prometheus instance managed by the Prometheus Operator to specify a .spec.serviceName in its configuration. This change allows individual instances to have their own dedicated Service resources. The motivation behind this feature is to provide modularity and stability by ensuring that changes to the Service configuration of one Prometheus instance do not affect other instances. This enhancement is particularly useful in environments where multiple Prometheus instances with different Thanos sidecar configurations are deployed.

Closes #6060

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)
• [X] 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

Please put a one-line changelog entry below. This will be copied to the changelog file during the release process.

Added support for individual Service resources per Prometheus instance via .spec.serviceName, allowing for greater isolation and independent management of Prometheus instances within a cluster.