test(e2e): add ServiceQuality-driven scale down prioritization test

[arnavgogia20]

Description

This PR adds an end-to-end test to validate ServiceQuality-driven scale-down behavior
for GameServerSets.

The test ensures that replicas marked with opsState: WaitToBeDeleted are prioritized
for deletion when scaling down, instead of following the default ordinal-based strategy.

Changes Made

• Added RestConfig to the E2E framework to support SPDY-based exec operations
• Introduced WaitForPodRunning helper to ensure deterministic exec behavior
• Implemented a new E2E test that:
  • Deploys a GameServerSet with 3 replicas
  • Applies a ServiceQuality using a file-existence check
  • Triggers WaitToBeDeleted on a specific replica via exec
  • Scales down the GameServerSet
  • Verifies the prioritized replica is deleted first
• Registered the test in the E2E test suite

Testing

• Verified locally on a Kubernetes cluster
• Test runs as part of the standard E2E suite

Related Issue

Fixes #292

[kruise-bot]

[APPROVALNOTIFIER] This PR is NOT APPROVED

This pull-request has been approved by:
Once this PR has been reviewed and has the lgtm label, please assign furykerry for approval by writing /assign @furykerry in a comment. For more information see:The Kubernetes Code Review Process.

The full list of commands accepted by this bot can be found here.

Details

Needs approval from an approver in each of these files:

• OWNERS

Approvers can indicate their approval by writing /approve in a comment
Approvers can cancel approval by writing /approve cancel in a comment

[kruise-bot]

Welcome @arnavgogia20! It looks like this is your first PR to openkruise/kruise-game 🎉

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 40.30%. Comparing base (aea10ee) to head (9f48e18).

Additional details and impacted files

@@           Coverage Diff           @@
##           master     #307   +/-   ##
=======================================
  Coverage   40.30%   40.30%           
=======================================
  Files         112      112           
  Lines       12499    12499           
=======================================
  Hits         5038     5038           
  Misses       7055     7055           
  Partials      406      406           

Flag	Coverage Δ
unittests	40.30% <ø> (ø)

Flags with carried forward coverage won't be shown. Click here to find out more.

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.

🚀 New features to boost your workflow:

• ❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.

[arnavgogia20]

Hii @furykerry @zmberg , the PR is ready with all the checks successful, please consider reviewing it, thankyouu