Use pod name as cluster check runner ID

[ahmed-mez]

What does this PR do?

Use the pod name as cluster check runner ID to allow deploying multiple cluster check runners on the same node. (Requires agent 7.27.0+)

Additional Notes

Related to DataDog/helm-charts#275

Describe your test plan

agent clusterchecks should show how the cluster agent identifies the runners by their pod names

[codecov-commenter]

Codecov Report

Merging #326 (09cc2f2) into main (022a88e) will increase coverage by 0.06%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##             main     #326      +/-   ##
==========================================
+ Coverage   58.43%   58.49%   +0.06%     
==========================================
  Files          60       60              
  Lines        6361     6371      +10     
==========================================
+ Hits         3717     3727      +10     
  Misses       2370     2370              
  Partials      274      274              

Flag	Coverage Δ
unittests	58.49% <100.00%> (+0.06%)	⬆️

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Impacted Files	Coverage Δ
controllers/datadogagent/clusterchecksrunner.go	76.85% <100.00%> (+0.65%)	⬆️

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