[CONTP-1363] feat(rbac): Add EndpointSlices read RBAC to clsuter agent

[Mathew-Estafanous]

What does this PR do?

Adds discovery.k8s.io/endpointslices RBAC permissions to DCA with get/list/watch permissions.

Motivation

As part of the Agent migration to endpointslices, the DCA needs RBAC permissions to read the resource group. The operator doesn't currently provide these permissions OOTB.

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: v7.77.x
• Cluster Agent: v7.77.x

Describe your test plan

1. Deploy custom operator.
2. Deploy default DatadogAgent CRD with minimal configurations.
3. Cluster role for DCA has discovery.k8s.io/endpointslices get/list/watch permissions.

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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 0% with 8 lines in your changes missing coverage. Please review.
✅ Project coverage is 38.80%. Comparing base (232e661) to head (6740b9d).

Files with missing lines	Patch %	Lines
...roller/datadogagent/component/clusteragent/rbac.go	0.00%	8 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #2705      +/-   ##
==========================================
- Coverage   38.81%   38.80%   -0.02%     
==========================================
  Files         307      307              
  Lines       26610    26618       +8     
==========================================
  Hits        10329    10329              
- Misses      15501    15509       +8     
  Partials      780      780              

Flag	Coverage Δ
unittests	38.80% <0.00%> (-0.02%)	⬇️

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

Files with missing lines	Coverage Δ
internal/controller/datadogagent_controller.go	66.66% <ø> (ø)
...roller/datadogagent/component/clusteragent/rbac.go	23.07% <0.00%> (-1.70%)	⬇️

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