Use same instance label value for network policies

[khewonc]

What does this PR do?

When creating the agent components, we set the instance label as <dda-name>-<component-suffix>. We need to use that as the pod selector when creating network policies or else they won't be targeting the correct pods.

Motivation

#1490

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

• Create a DDA with network policies enabled:

spec:
  global:
    networkPolicy:
      create: true
      flavor: kubernetes

• Check that the network policy pod selector uses the same instance label value that's on the corresponding pod. Example:

$ kubectl get networkpolicy
datadog-agent-agent                   app.kubernetes.io/instance=datadog-agent-agent,app.kubernetes.io/part-of=default-datadog--agent                   7h56m

The label key and value app.kubernetes.io/instance=datadog-agent-agent from the network policy should match the agent pod's instance label key and value. Double check that the part of labels match as well:

$ kubectl describe pod <agent-pod>
Labels:           agent.datadoghq.com/component=agent
                  [...]
                  app.kubernetes.io/instance=datadog-agent-agent
                  [...]
                  app.kubernetes.io/part-of=default-datadog--agent

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 50.00000% with 1 line in your changes missing coverage. Please review.

Project coverage is 48.62%. Comparing base (b70d772) to head (2c4570e).
Report is 1 commits behind head on main.

Files with missing lines	Patch %	Lines
...ntroller/datadogagent/component/objects/network.go	50.00%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #1509      +/-   ##
==========================================
- Coverage   48.63%   48.62%   -0.02%     
==========================================
  Files         227      227              
  Lines       20223    20219       -4     
==========================================
- Hits         9836     9832       -4     
  Misses       9871     9871              
  Partials      516      516              

Flag	Coverage Δ
unittests	48.62% <50.00%> (-0.02%)	⬇️

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

Files with missing lines	Coverage Δ
...ntroller/datadogagent/component/objects/network.go	2.63% <50.00%> (-0.68%)	⬇️

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