Enable otel-agent using DDA annotation

[levan-m]

What does this PR do?

Adds a logic to enable otel-agent using annotation on DatadogAgent.

Sample DDA metadata with the annotation to enable otel-agent container.

apiVersion: datadoghq.com/v2alpha1
kind: DatadogAgent
metadata:
  annotations:
    agent.datadoghq.com/otel-agent-enabled: "true"
...

Motivation

What inspired you to submit this pull request?

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

Attention: Patch coverage is 57.14286% with 3 lines in your changes missing coverage. Please review.

Project coverage is 48.70%. Comparing base (ae5b9e1) to head (a05e26e).

Files with missing lines	Patch %	Lines
...ller/datadogagent/feature/enabledefault/feature.go	0.00%	2 Missing and 1 partial ⚠️

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #1475   +/-   ##
=======================================
  Coverage   48.70%   48.70%           
=======================================
  Files         224      224           
  Lines       19845    19852    +7     
=======================================
+ Hits         9665     9669    +4     
- Misses       9673     9675    +2     
- Partials      507      508    +1     

Flag	Coverage Δ
unittests	48.70% <57.14%> (+<0.01%)	⬆️

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

Files with missing lines	Coverage Δ
api/datadoghq/v2alpha1/test/builder.go	92.00% <100.00%> (+0.05%)	⬆️
...ller/datadogagent/feature/enabledefault/feature.go	34.57% <0.00%> (-0.39%)	⬇️

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