PoC constructor coverage refactor

[tbavelier]

What does this PR do?

PoC refactor for static constructors: move probe and RBAC literals into templates and return copied values.

Motivation

Improve useful coverage without adding tests that only restate constructor bodies.

Additional Notes

Stacked on #3020. Uses DeepCopy() for Kubernetes probes and slices.Clone for RBAC rule slices to avoid shared mutable defaults.

Minimum Agent Versions

• Agent: N/A
• Cluster Agent: N/A

Describe your test plan

go test ./pkg/constants ./pkg/kubernetes/rbac ./internal/controller/datadogagent/component/agent ./internal/controller/datadogagent/component/clusterchecksrunner ./internal/controller/datadogagent/component/otelagentgateway -cover -timeout 90s
go test ./internal/controller/datadogagent/... ./pkg/constants ./pkg/kubernetes/rbac -timeout 120s

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
• All commits are signed (see: signing commits)

[codecov-commenter]

Codecov Report

❌ Patch coverage is 79.59184% with 10 lines in your changes missing coverage. Please review.
✅ Project coverage is 47.71%. Comparing base (f09c127) to head (38af679).

Files with missing lines	Patch %	Lines
pkg/constants/utils.go	33.33%	8 Missing ⚠️
...er/datadogagent/component/otelagentgateway/rbac.go	0.00%	2 Missing ⚠️

Additional details and impacted files

@@                            Coverage Diff                            @@
##           tbavelier/improve-coverage-quick-wins    #3021      +/-   ##
=========================================================================
- Coverage                                  47.72%   47.71%   -0.02%     
=========================================================================
  Files                                        331      332       +1     
  Lines                                      28322    28145     -177     
=========================================================================
- Hits                                       13518    13430      -88     
+ Misses                                     13976    13887      -89     
  Partials                                     828      828              

Flag	Coverage Δ
unittests	47.71% <79.59%> (-0.02%)	⬇️

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

Files with missing lines	Coverage Δ
...al/controller/datadogagent/component/agent/rbac.go	100.00% <100.00%> (ø)
...datadogagent/component/clusterchecksrunner/rbac.go	100.00% <100.00%> (ø)
pkg/kubernetes/rbac/utils.go	100.00% <100.00%> (ø)
...er/datadogagent/component/otelagentgateway/rbac.go	0.00% <0.00%> (ø)
pkg/constants/utils.go	85.91% <33.33%> (+43.37%)	⬆️

---

Continue to review full report in Codecov by Sentry.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update f09c127...38af679. Read the comment docs.

🚀 New features to boost your workflow:

• ❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.

[datadog-prod-us1-5]

🎯 Code Coverage (details)
• Patch Coverage: 86.84%
• Overall Coverage: 48.26% (-0.02%)

_{This comment will be updated automatically if new data arrives.
🔗 Commit SHA: 38af679 | Docs | Datadog PR Page | Give us feedback!}