chore(e2e): build resources using builder functions

[NawafSwe]

Motivation

Currently, many e2e tests use hardcoded YAML strings and fmt.Sprintf-based helper functions to create test resources. This approach has several drawbacks:

1. Function name bloat: As noted in #11279, this leads to unwieldy function names like MTLSMeshWithMeshServicesAndMetricsKubernetes when we need to support various field combinations.

2. Maintainability: Static YAML strings scattered throughout test files are harder to maintain and refactor when resource schemas change.

3. Type safety: String-based YAML generation lacks compile-time validation and IDE support.

This PR addresses these issues by replacing static YAML strings with the existing builder pattern that's already used in unit tests, following the approach suggested in the issue comments.

Changes

This PR replaces hardcoded YAML strings with builder functions in e2e tests:

• test/e2e_env/multizone/localityawarelb/meshmultizoneservice.go: Replaced static MeshMultiZoneService YAML with builders.MeshMultiZoneService() builder pattern using method chaining.

• test/e2e_env/multizone/externalservices/externalservices_multizone_universal.go: Fixed incorrect usage of ResourceUniversal() to properly use the builder pattern.

Benefits

• Better maintainability: Changes to resource schemas are easier to propagate through tests
• Type safety: Compile-time validation and IDE autocomplete support
• Readability: Fluent builder API is more readable than YAML strings
• Consistency: Aligns e2e tests with the builder pattern already used in unit tests
• Extensibility: Easy to add new field combinations without creating new function variants

Future work

This PR focuses on MeshMultiZoneService as a starting point. Additional resources (such as MeshLoadBalancingStrategy) still use static YAML and can be migrated in follow-up PRs as builders become available.

Related issues

Addresses #11294 and the concerns raised in #11279.

Changelog: skip

[Copilot]

Pull request overview

This PR refactors E2E tests to use builder functions instead of hardcoded YAML strings for creating test resources. The change improves maintainability and type safety by replacing inline YAML with programmatic resource construction.

Changes:

• Replaced inline YAML string with builder pattern for MeshMultiZoneService resource
• Added import for samples package containing the builder functions

[github-actions]

Reviewer Checklist

🔍 Each of these sections need to be checked by the reviewer of the PR 🔍:
If something doesn't apply please check the box and add a justification if the reason is non obvious.

• Is the PR title satisfactory? Is this part of a larger feature and should be grouped using > Changelog?
• PR description is clear and complete. It Links to relevant issue as well as docs and UI issues
• This will not break child repos: it doesn't hardcode values (.e.g "kumahq" as an image registry)
• IPv6 is taken into account (.e.g: no string concatenation of host port)
• Tests (Unit test, E2E tests, manual test on universal and k8s)
  • Don't forget ci/ labels to run additional/fewer tests
• Does this contain a change that needs to be notified to users? In this case, UPGRADE.md should be updated.
• Does it need to be backported according to the backporting policy? (this GH action will add "backport" label based on these file globs, if you want to prevent it from adding the "backport" label use no-backport-autolabel label)

[NawafSwe]

@slonka , I am unable to run the e2e tests locally, it would be great If you allow me to trigger the CI here 🙌

[slonka]

@NawafSwe thanks for the contribution. Left one comment. Let the PR run. You need to signoff the commits with --signoff.

[NawafSwe]

@slonka All commits signed off sir!

[NawafSwe]

I reopened the PR here
@slonka