Added DNSpolicy and DNSConfig overrides

[Eokye]

What does this PR do?

CECO-1252(https://datadoghq.atlassian.net/browse/CECO-1252
DNS config and DNS policy overrides were migrated to v2 from v1. This change fixes that.

A brief description of the change being made with this pull request.
DNS config + policy added to overrides and unit tested.

Motivation

What inspired you to submit this pull request?
#1144
https://datadoghq.atlassian.net/browse/CONS-6318

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

Used this manifest for the datadog-agent on a kind local cluster:

apiVersion: datadoghq.com/v2alpha1
kind: DatadogAgent
metadata:
  name: datadog
spec:
  override:
    nodeAgent:
      image:
        name: gcr.io/datadoghq/agent:7.55.0-rc.3
      dnsPolicy: ClusterFirstWithHostNet
      dnsConfig: 
        nameservers:
        - 10.9.8.7
        - 10.9.7.4
    clusterAgent:
      image:
        name: gcr.io/datadoghq/cluster-agent:7.55.0-rc.3
    clusterChecksRunner:
      image:
        name: gcr.io/datadoghq/agent:7.55.0-rc.3
  global:
    clusterName: kind-control
    kubelet:
      tlsVerify: false
    site: datadoghq.com
    credentials:
      apiSecret:
        secretName: datadog-secret
        keyName: api-key

The resulting change in the agent pod CRD:

  dnsConfig:
    nameservers:
    - 10.9.8.7
    - 10.9.7.4
  dnsPolicy: ClusterFirstWithHostNet

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

[github-actions]

This pull request does not contain a valid label. Please add one of the following labels: bug, enhancement, refactoring, documentation, tooling, dependencies

[codecov-commenter]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 59.34%. Comparing base (c46b61d) to head (b74a4fb).
Report is 1 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #1233      +/-   ##
==========================================
+ Coverage   59.33%   59.34%   +0.01%     
==========================================
  Files         177      177              
  Lines       22371    22377       +6     
==========================================
+ Hits        13273    13279       +6     
  Misses       8286     8286              
  Partials      812      812              

Flag	Coverage Δ
unittests	59.34% <100.00%> (+0.01%)	⬆️

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

Files	Coverage Δ
apis/datadoghq/v2alpha1/datadogagent_types.go	100.00% <ø> (ø)
...ntrollers/datadogagent/override/podtemplatespec.go	72.72% <100.00%> (+0.56%)	⬆️

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