[2/N][Refactor] Run golangci-lint for apiserver

[MortalHappiness]

Why are these changes needed?

Based on the rules in https://github.com/ray-project/kuberay/pull/2128, run golangci-lint run --fix --exclude-files _generated.go\|datafile.go under the apiserver directory.

Related issue number

N/A

Checks

• [x] I've made sure the tests are passing.
• Testing Strategy
  • [ ] Unit tests
  • [x] Manual tests
  • [ ] This PR is not tested :(