fix: wss related tests are unstable

[AlinsRan]

Type of change:

• Bugfix
• New feature provided
• Improve performance
• Backport patches
• Documentation
• Refactor
• Chore
• CI/CD or Tests

What this PR does / why we need it:

• Fix gateway resource isolation issue caused by missing controllerName validation

This commit fixes an issue where the Gateway resource did not validate the controllerName field.
Without this check, multiple controllers could reconcile the same Gateway resource, leading to resource conflicts and unstable test behavior.

https://github.com/apache/apisix-ingress-controller/actions/runs/20014615226/job/57393721934#step:13:19681

Pre-submission checklist:

• Did you explain what problem does this PR solve? Or what new features have been added?
• Have you added corresponding test cases?
• Have you modified the corresponding document?
• Is this PR backward compatible? If it is not backward compatible, please discuss on the mailing list first