(No-op) SA1019: Remove deprecated functions usage

[tbavelier]

What does this PR do?

• Replaces all deprecated functions with the modern equivalent

Motivation

• Same as (No-op) Remove duplicate imports #2420 : Reduce number of staticcheck linter (disabled for now) violations

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

Write there any instructions and details you may have to test your PR.

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 0% with 15 lines in your changes missing coverage. Please review.
✅ Project coverage is 37.31%. Comparing base (afdebbc) to head (edde844).

Files with missing lines	Patch %	Lines
pkg/controller/utils/datadog/metrics_forwarder.go	0.00%	7 Missing ⚠️
cmd/check-operator/upgrade/upgrade.go	0.00%	2 Missing ⚠️
cmd/helpers/secrets/secrets.go	0.00%	2 Missing ⚠️
cmd/kubectl-datadog/flare/flare.go	0.00%	2 Missing ⚠️
cmd/kubectl-datadog/agent/check/check.go	0.00%	1 Missing ⚠️
hack/generate-docs/generate-docs.go	0.00%	1 Missing ⚠️

Additional details and impacted files

@@                         Coverage Diff                         @@
##           tbavelier/remove-embedded-field    #2422      +/-   ##
===================================================================
- Coverage                            37.32%   37.31%   -0.01%     
===================================================================
  Files                                  290      290              
  Lines                                24720    24725       +5     
===================================================================
  Hits                                  9226     9226              
- Misses                               14781    14786       +5     
  Partials                               713      713              

Flag	Coverage Δ
unittests	37.31% <0.00%> (-0.01%)	⬇️

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

Files with missing lines	Coverage Δ
cmd/kubectl-datadog/agent/check/check.go	9.65% <0.00%> (ø)
hack/generate-docs/generate-docs.go	0.00% <0.00%> (ø)
cmd/check-operator/upgrade/upgrade.go	0.00% <0.00%> (ø)
cmd/helpers/secrets/secrets.go	0.00% <0.00%> (ø)
cmd/kubectl-datadog/flare/flare.go	0.00% <0.00%> (ø)
pkg/controller/utils/datadog/metrics_forwarder.go	31.63% <0.00%> (-0.34%)	⬇️

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