actually update branched image tag in all jobs, not just parent config

[mikemorris]

This appears to be an oversight where the image was not being updated to the branched tag in all jobs, only in the parent config. I believe this should replace the need for the following manual part of Step 3 as described in istio/istio#54707

In the job configs prow/**/*-1.25.yaml, replace any image build-tools(-centos|-proxy):master with build-tools(-centos|-proxy):release-1.25. This is easy to do in VSCode, like this:

Additionally, filters out duplicate env vars in all jobs to replace the need for the following other manual part of Step 3,
refs https://pkg.go.dev/k8s.io/api/core/v1#EnvVar

Remove duplicated env entries of the following in the configs (you can use a similar search in VSCode as above, but beware, it'll only match the indentation level that you specify if you have strict matching enabled.):

- name: BUILD_WITH_CONTAINER
  value: "0"

Finally, adds logging for commands needed to retag images when running with --skip-gar-tagging and updates some minor deprecated filesystem calls.

/cc @kfaseela @dhawton

[mikemorris]

/hold

Going to add the duplicate env removal on top of this since it's now actually iterating over all jobs.

[mikemorris]

/unhold

Tested locally and this appears to be working as intended now.

[kfaseela]

@mikemorris : this LGTM. I just added a hold in case you have anything else to verify or want @howardjohn to do a review before merging. Feel free to remove the dnm when you want to merge it