[AGENTONB-2674] Use k8s watches for helm metadata forwarder

[swang392]

What does this PR do?

Using helm watch instead of a cache and list mechanism for tracking and forwarding helm metadata

Motivation

Helm List was costly in CPU. With the previous cache mechanism, metadata wasn't emitted to REDAPL immediately, instead waiting until the cached helm releases expired before sending a new payload.

Additional Notes

Anything else we should know when reviewing?

Minimum Agent Versions

Are there minimum versions of the Datadog Agent and/or Cluster Agent required?

• Agent: vX.Y.Z
• Cluster Agent: vX.Y.Z

Describe your test plan

• install operator via helm, with debug logging enabled

❯ helm install datadog-operator datadog/datadog-operator --set image.doNotCheckTag=true --set image.repository=operator --set logLevel="debug"  --set installCRDs=true --set clusterName=sarah-dev --set image.tag=metadata-58

• Check logs to ensure that the metadata forwarder has started up, Starting metadata forwarder and that the payload for the latest release/revision number of the datadog-operator chart has been sent. For example,

{"level":"DEBUG","ts":"2025-12-29T16:24:15.065Z","logger":"metadata.helm","msg":"Processing new/updated Helm release from Secret","release":"datadog-operator","namespace":"default","revision":4}

• To check the watch mechanism, install the datadog chart, since upgrading the datadog-operator chart would cause the operator pod (and thus the metadata forwarder) to restart. Set datadog.operator.enabled=false to prevent any issues during installation.
• Check that the operator logs register the new Helm release and send the payload:

{"level":"DEBUG","ts":"2025-12-29T16:50:47.266Z","logger":"metadata.helm","msg":"Processing new/updated Helm release from Secret","release":"datadog","namespace":"default","revision":2}
{"level":"DEBUG","ts":"2025-12-29T16:50:47.267Z","logger":"metadata.helm","msg":"Sending metadata to URL","url":"https://app.datadoghq.com/api/v1/metadata"}
{"level":"DEBUG","ts":"2025-12-29T16:50:47.287Z","logger":"metadata.helm","msg":"Read metadata response","release":"datadog","status_code":202}
{"level":"DEBUG","ts":"2025-12-29T16:50:47.287Z","logger":"metadata.helm","msg":"Successfully sent metadata for Helm release","release":"datadog","namespace":"default","revision":2}

tested on gizmo

Checklist

• PR has at least one valid label: bug, enhancement, refactoring, documentation, tooling, and/or dependencies
• PR has a milestone or the qa/skip-qa label

[codecov-commenter]

Codecov Report

❌ Patch coverage is 2.09205% with 234 lines in your changes missing coverage. Please review.
✅ Project coverage is 37.14%. Comparing base (d39479a) to head (8712ab7).

Files with missing lines	Patch %	Lines
pkg/controller/utils/metadata/helm_metadata.go	2.14%	228 Missing ⚠️
cmd/main.go	0.00%	6 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #2437      +/-   ##
==========================================
- Coverage   37.32%   37.14%   -0.18%     
==========================================
  Files         290      290              
  Lines       24720    24818      +98     
==========================================
- Hits         9226     9219       -7     
- Misses      14781    14886     +105     
  Partials      713      713              

Flag	Coverage Δ
unittests	37.14% <2.09%> (-0.18%)	⬇️

Flags with carried forward coverage won't be shown. Click here to find out more.

Files with missing lines	Coverage Δ
cmd/main.go	6.55% <0.00%> (-0.07%)	⬇️
pkg/controller/utils/metadata/helm_metadata.go	20.17% <2.14%> (-10.60%)	⬇️

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