Update VERSIONS_YAML_FILE e2e test information

[fjglira]

What type of PR is this?

• Enhancement / New Feature
• Bug Fix
• Refactor
• Optimization
• Test
• Documentation Update

What this PR does / why we need it:

Update information related to the VERSIONS_YAML_FILE for running test

Which issue(s) this PR fixes:

Fixes #

Related Issue/PR #

Additional information:

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 76.93%. Comparing base (72035af) to head (17d013f).
Report is 7 commits behind head on main.

Additional details and impacted files

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##             main     #916   +/-   ##
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  Coverage   76.93%   76.93%           
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  Files          44       44           
  Lines        2679     2679           
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  Hits         2061     2061           
  Misses        524      524           
  Partials       94       94           

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[sridhargaddam]

@fjglira some tiny nits, otherwise LGTM.

[FilipB]

with the default value being pkg/istioversion/versions.yaml
This is a bit confusing, it looks like VERSIONS_YAML_FILE should contain a path but it's not true.
We are using following evn vars to create full path to the file:
VERSIONS_YAML_DIR
VERSIONS_YAML_FILE

[fjglira]

Hey @FilipB, but VERSIONS_YAML_DIR is just used in the chart generation and removal of old istio charts, but if you try to run the test with this var, we will get this error, for example:

2025-06-18T10:36:27.306192Z	info	loading supported istio versions from customversion.yaml
panic: failed to read versions from 'customversion.yaml': open customversion.yaml: file does not exist

This is because of the version.go package is using embed to get the version yaml file and is using only the env var VERSIONS_YAML_FILE when it is init

func init() {
	// we can't use ldflags when running tests, use an env variable instead
	// tmp workaround for https://github.com/golang/go/issues/64246
	if versionsFilename == "" {
		versionsFilename = env.Get("VERSIONS_YAML_FILE", "versions.yaml")
	}
	log.Info("loading supported istio versions from " + versionsFilename)
	// Read the embedded versions.yaml file
	data, err := versionsFiles.ReadFile(versionsFilename)
	if err != nil {
		panic(fmt.Errorf("failed to read versions from '%s': %w", versionsFilename, err))
	}

	List, Default, Base, New, Map, aliasList, EOL = mustParseVersionsYaml(data)
}

Go disallows other paths in //go: embed paths, to be able to use it as we need to place it in the same directory as the go function

[fjglira]

I'll rephrase the sentence in the doc to clarify that the file must be located there and we just need to provide the file name

[dgn]

/cherry-pick release-1.26

[istio-testing]

@dgn: new pull request created: #981

Details

In response to this:

/cherry-pick release-1.26

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