fix: fix race condition in start controllers

[mozillazg]

What this PR does / why we need it:

gatekeeper/vendor/sigs.k8s.io/controller-runtime/pkg/source/source.go

Lines 251 to 254 in 19c9cef

	// use default value if DestBufferSize not specified
	if cs.DestBufferSize == 0 {
	cs.DestBufferSize = defaultBufferSize
	}

Before:

==================
WARNING: DATA RACE
Read at 0x00c00004f118 by goroutine 226:
  sigs.k8s.io/controller-runtime/pkg/source.(*Channel).Start()
      /go/src/github.com/open-policy-agent/gatekeeper/vendor/sigs.k8s.io/controller-runtime/pkg/source/source.go:252 +0xd3
  sigs.k8s.io/controller-runtime/pkg/internal/controller.(*Controller).Start.func2()
      /go/src/github.com/open-policy-agent/gatekeeper/vendor/sigs.k8s.io/controller-runtime/pkg/internal/controller/controller.go:180 +0x942
  sigs.k8s.io/controller-runtime/pkg/internal/controller.(*Controller).Start()
      /go/src/github.com/open-policy-agent/gatekeeper/vendor/sigs.k8s.io/controller-runtime/pkg/internal/controller/controller.go:234 +0x2b5
  sigs.k8s.io/controller-runtime/pkg/manager.(*runnableGroup).reconcile.func1()
      /go/src/github.com/open-policy-agent/gatekeeper/vendor/sigs.k8s.io/controller-runtime/pkg/manager/runnable_group.go:218 +0x1cb
  sigs.k8s.io/controller-runtime/pkg/manager.(*runnableGroup).reconcile·dwrap·12()
      /go/src/github.com/open-policy-agent/gatekeeper/vendor/sigs.k8s.io/controller-runtime/pkg/manager/runnable_group.go:221 +0x47

Previous write at 0x00c00004f118 by goroutine 335:
  sigs.k8s.io/controller-runtime/pkg/source.(*Channel).Start()
      /go/src/github.com/open-policy-agent/gatekeeper/vendor/sigs.k8s.io/controller-runtime/pkg/source/source.go:253 +0xec
  sigs.k8s.io/controller-runtime/pkg/internal/controller.(*Controller).Start.func2()
      /go/src/github.com/open-policy-agent/gatekeeper/vendor/sigs.k8s.io/controller-runtime/pkg/internal/controller/controller.go:180 +0x942
  sigs.k8s.io/controller-runtime/pkg/internal/controller.(*Controller).Start()
      /go/src/github.com/open-policy-agent/gatekeeper/vendor/sigs.k8s.io/controller-runtime/pkg/internal/controller/controller.go:234 +0x2b5
  sigs.k8s.io/controller-runtime/pkg/manager.(*runnableGroup).reconcile.func1()
      /go/src/github.com/open-policy-agent/gatekeeper/vendor/sigs.k8s.io/controller-runtime/pkg/manager/runnable_group.go:218 +0x1cb
  sigs.k8s.io/controller-runtime/pkg/manager.(*runnableGroup).reconcile·dwrap·12()
      /go/src/github.com/open-policy-agent/gatekeeper/vendor/sigs.k8s.io/controller-runtime/pkg/manager/runnable_group.go:221 +0x47

Goroutine 226 (running) created at:
  sigs.k8s.io/controller-runtime/pkg/manager.(*runnableGroup).reconcile()
      /go/src/github.com/open-policy-agent/gatekeeper/vendor/sigs.k8s.io/controller-runtime/pkg/manager/runnable_group.go:202 +0x23c
  sigs.k8s.io/controller-runtime/pkg/manager.(*runnableGroup).Start.func1·dwrap·11()
      /go/src/github.com/open-policy-agent/gatekeeper/vendor/sigs.k8s.io/controller-runtime/pkg/manager/runnable_group.go:131 +0x39

Goroutine 335 (running) created at:
  sigs.k8s.io/controller-runtime/pkg/manager.(*runnableGroup).reconcile()
      /go/src/github.com/open-policy-agent/gatekeeper/vendor/sigs.k8s.io/controller-runtime/pkg/manager/runnable_group.go:202 +0x23c
  sigs.k8s.io/controller-runtime/pkg/manager.(*runnableGroup).Start.func1·dwrap·11()
      /go/src/github.com/open-policy-agent/gatekeeper/vendor/sigs.k8s.io/controller-runtime/pkg/manager/runnable_group.go:131 +0x39
==================
    core.go:90: ...
    testing.go:1152: race detected during execution of test
--- FAIL: Test_Tracker (1.69s)

After:

--- PASS: Test_Tracker (1.68s)

Which issue(s) this PR fixes (optional, using fixes #<issue number>(, fixes #<issue_number>, ...) format, will close the issue(s) when the PR gets merged):

#1929

Special notes for your reviewer:

[codecov-commenter]

Codecov Report

Merging #1941 (a24dce5) into master (6c58cad) will increase coverage by 0.04%.
The diff coverage is 0.00%.

@@            Coverage Diff             @@
##           master    #1941      +/-   ##
==========================================
+ Coverage   53.23%   53.28%   +0.04%     
==========================================
  Files         100      100              
  Lines        8986     8986              
==========================================
+ Hits         4784     4788       +4     
+ Misses       3809     3806       -3     
+ Partials      393      392       -1     

Flag	Coverage Δ
unittests	53.28% <0.00%> (+0.04%)	⬆️

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

Impacted Files	Coverage Δ
pkg/mutation/schema/schema.go	80.76% <0.00%> (ø)
pkg/watch/replay.go	81.25% <0.00%> (+2.27%)	⬆️

---

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[maxsmythe]

Thanks for the fix! LGTM

[ritazh]

LGTM
Thanks @mozillazg!