Fix listing issues reported by staticcheck

[jjngx]

Staticcheck reports following issues:

➜  kubernetes-ingress git:(main) staticcheck ./...
internal/certmanager/test_files/reactors.go:49:14: type assertion to the same type: createAction.GetObject() already has type runtime.Object (S1040)
internal/certmanager/test_files/util.go:26:2: rand.Seed has been deprecated since Go 1.20 and an alternative has been available since Go 1.0: Programs that call Seed and then expect a specific sequence of results from the global random source (using functions such as Int) can be broken when a dependency changes how much it consumes from the global random source. To avoid such breakages, programs that need a specific result sequence should use NewRand(NewSource(seed)) to obtain a random generator that other packages cannot access.  (SA1019)
internal/k8s/appprotect/app_protect_configuration.go:281:84: error strings should not be capitalized (ST1005)
internal/k8s/appprotect/app_protect_configuration.go:293:74: error strings should not be capitalized (ST1005)
internal/k8s/appprotect/app_protect_configuration.go:402:15: error strings should not be capitalized (ST1005)
internal/k8s/appprotect/app_protect_configuration.go:410:15: error strings should not be capitalized (ST1005)
internal/k8s/appprotect/app_protect_configuration.go:418:15: error strings should not be capitalized (ST1005)
internal/k8s/appprotect/app_protect_configuration.go:420:14: error strings should not be capitalized (ST1005)
internal/k8s/appprotect/app_protect_configuration.go:602:15: error strings should not be capitalized (ST1005)
internal/k8s/appprotect/app_protect_configuration.go:607:15: error strings should not be capitalized (ST1005)
internal/k8s/appprotect/app_protect_configuration.go:609:14: error strings should not be capitalized (ST1005)
internal/k8s/secrets/validation.go:47:10: error strings should not be capitalized (ST1005)
internal/k8s/secrets/validation.go:81:10: error strings should not be capitalized (ST1005)
internal/k8s/secrets/validation.go:84:10: error strings should not be capitalized (ST1005)
internal/k8s/secrets/validation.go:89:10: error strings should not be capitalized (ST1005)
internal/k8s/secrets/validation.go:115:10: error strings should not be capitalized (ST1005)
internal/k8s/secrets/validation.go:119:10: error strings should not be capitalized (ST1005)
internal/k8s/secrets/validation.go:152:9: error strings should not be capitalized (ST1005)

Consider this a QA issue.

➜  kubernetes-ingress git:(main) staticcheck --version
staticcheck 2023.1.3 (v0.4.3)