Only add the test container to cache once

[lucacome]

• Builds the container and adds it to cache once before starting all the tests
• Skips running the tests on tag

[codecov-commenter]

Codecov Report

Merging #3518 (fb618ea) into main (879efeb) will decrease coverage by 0.03%.
The diff coverage is n/a.

❗ Current head fb618ea differs from pull request most recent head deaf037. Consider uploading reports for the commit deaf037 to get more accurate results

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@@            Coverage Diff             @@
##             main    #3518      +/-   ##
==========================================
- Coverage   52.00%   51.98%   -0.03%     
==========================================
  Files          60       60              
  Lines       16816    16816              
==========================================
- Hits         8746     8742       -4     
- Misses       7775     7777       +2     
- Partials      295      297       +2     

Impacted Files	Coverage Δ
internal/k8s/configuration.go	95.43% <0.00%> (-0.37%)	⬇️

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