Backport of [net-7710] don't overwrite prometheus path annotation if it's already been specified into release/1.4.x

[hc-github-team-consul-core]

Backport

This PR is auto-generated from #3846 to be assessed for backporting due to the inclusion of the label backport/1.4.x.

The below text is copied from the body of the original PR.

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Changes proposed in this PR

• Addresses Helm chart: User provided annotations should supersed default ones #1970
• The issue specifically mentions client prometheus annotations, but I went ahead and made the change for all the places we have the prometheus path annotation. I only included the path annotation (rather than scrape and port) because the scrape and port annotations shouldn't change-- if metrics are enabled then scrape should be true and the port is hardcoded.

How I've tested this PR

How I expect reviewers to test this PR

Checklist

• Tests added
• CHANGELOG entry added

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Overview of commits

• 94c3412