fix(common): apply registry override to image args

[pujitha24]

Changes

Fixes TEKTON_REGISTRY_OVERRIDE not being applied to images passed as container CLI args (e.g. -workingdirinit-image, -el-image, -shell-image-win).

TEKTON_REGISTRY_OVERRIDE is documented as a way to rewrite the registry for every image the operator deploys, but only container.Image, Task step images, and StepAction images had a fallback that applies it when no per-image env var is set. Images passed as container CLI args were skipped by that fallback, so in an air-gapped install those container args still pointed at the public upstream registries (gcr.io, mcr.microsoft.com) even with TEKTON_REGISTRY_OVERRIDE set, unless the user also set every documented per-image env var individually.

replaceContainersArgsImage (pkg/reconciler/common/transformers.go) only rewrote an arg's image when a matching per-image env var existed. This adds the same registry-override fallback already used by replaceContainerImages/replaceStepsImages/replaceStepActionImages: when no per-image override matches an arg whose flag name looks like an image flag (contains _image once normalized, covering both -foo-image and -foo-image-win style flags), it rewrites just its registry domain via TEKTON_REGISTRY_OVERRIDE.

Added TestDeploymentContainerArgsImagesRegistryOverrideFallback to pkg/reconciler/common/transformers_test.go, covering both a plain -bash-image arg and the real -shell-image-win flag shipped in the Tekton Pipeline controller manifest. Confirmed (by temporarily reverting the transformers.go change) that this test fails without the fix and passes with it.

Report: #3270

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Release Notes

Fix `TEKTON_REGISTRY_OVERRIDE` not being applied to image
references passed as container args (e.g. entrypoint, nop,
workingdirinit, shell-image-win, and triggers' event-listener
sink images).

---

AI assistance: this change was drafted with Claude Code.

Fixes #3270

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[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 26.13%. Comparing base (aadfe5a) to head (8d0e821).
⚠️ Report is 1 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #3885      +/-   ##
==========================================
- Coverage   26.13%   26.13%   -0.01%     
==========================================
  Files         465      465              
  Lines       24933    24937       +4     
==========================================
+ Hits         6516     6517       +1     
- Misses      17697    17698       +1     
- Partials      720      722       +2     

Flag	Coverage Δ
unit-tests	26.13% <ø> (-0.01%)	⬇️

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