Fix data race in TestCRD

[jpbetz]

Fix this race:

==================
WARNING: DATA RACE
Write at 0x00c42a845350 by goroutine 748:
  k8s.io/kubernetes/cmd/kube-apiserver/app/testing.TestCRD()
      cmd/kube-apiserver/app/testing/server_test.go:257 +0x15da
  testing.tRunner()
      /root/.cache/bazel/_bazel_root/e9f728bbd90b3fba632eb31b20e1dacd/external/go_sdk/src/testing/testing.go:746 +0x16c

Previous write at 0x00c42a845350 by goroutine 481:
  k8s.io/kubernetes/cmd/kube-apiserver/app/testing.TestCRD.func2()
      cmd/kube-apiserver/app/testing/server_test.go:250 +0x241

Related to #54095

[lavalamp]

/lgtm
/approve

[cblecker]

/release-note-none

[k8s-github-robot]

[APPROVALNOTIFIER] This PR is NOT APPROVED

This pull-request has been approved by: jpbetz, lavalamp

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[cblecker]

cc: @sttts
Related to #54095

[jpbetz]

/retest

[jpbetz]

/retest

[k8s-github-robot]

Automatic merge from submit-queue (batch tested with PRs 55092, 55348, 55095, 55277, 55352). If you want to cherry-pick this change to another branch, please follow the instructions here.