operator: support custom dashboard service labels and annotations (backport #14115)

[mergify[bot]]

Unlike other components, the Ceph dashboard Service object could not be configured with custom labels and annotations. This can be useful when integrating Rook into a cluster with custom controllers similarly to how the RGW service is customized.

Issue resolved by this Pull Request: Resolves #14111

Checklist:

• [x] Commit Message Formatting: Commit titles and messages follow guidelines in the developer guide.
• [x] Reviewed the developer guide on Submitting a Pull Request
• [x] Pending release notes updated with breaking and/or notable changes for the next minor release.
• [x] Documentation has been updated, if necessary.
• [ ] Unit tests have been added, if necessary.
• [ ] Integration tests have been added, if necessary.

Let me know if you'd like a unit test!

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This is an automatic backport of pull request #14115 done by Mergify.