feat(ruler): add labels support to rule groups

[sugaf1204]

What this PR does / why we need it:

This PR adds support for rule group level labels, a feature introduced in Prometheus 3.0+. This allows
users to define common labels at the group level that will be applied to all rules within the group.

Which issue(s) this PR fixes:
Fixes #

Special notes for your reviewer:

Checklist

• Reviewed the CONTRIBUTING.md guide
  (required)
• Documentation added
• Tests updated
• Title matches the required conventional commits format, see
  here
• Changes that require user attention or interaction to upgrade are documented in
  docs/sources/setup/upgrade/_index.md
• If the change is deprecating or removing a configuration option, update the deprecated-config.yaml
  and deleted-config.yaml files respectively in the tools/deprecated-config-checker directory. Example
  PR