[kong] add servicemonitor targetLabels support

[flabatut]

related to prometheus-operator
serviceMonitor CRD capacity to transfer
kubernetes service labels to prometheus
when using targetLabels spec parameter
See https://tinyurl.com/yclly9xx for additional information

What this PR does / why we need it:

Which issue this PR fixes

(optional, in fixes #<issue number>(, fixes #<issue_number>, ...) format, will close that issue when PR gets merged)

• fixes #

Special notes for your reviewer:

Checklist

[Place an '[x]' (no spaces) in all applicable fields. Please remove unrelated fields.]

• PR is based off the current tip of the next branch and targets next, not master
• New or modified sections of values.yaml are documented in the README.md
• Title of the PR and commit headers start with chart name (e.g. [kong])

[CLAassistant]

All committers have signed the CLA.

[rainest]

@flabatut for the future, please avoid including unrelated changes (the controller version bump) in PRs, or separate them into atomic commits to keep history clear. That's useful for when we write the changelog later.

Went ahead and merged as-is since that change is small and should go into next anyway. However, tt's usually not necessary to PR them--we go through and bump up versions where needed during release prep, before we merge current next to master and create a new chart version.

[hbagdi]

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