Automatic merge from submit-queue (batch tested with PRs 43681, 40423, 43562, 43008, 43381)

k8s.io/apiserver: make maxRetryWhenPatchConflicts public

This variable used to be public (before https://github.com/kubernetes/kubernetes/pull/37468). It is pretty use-full to write reliable integration tests that involve resource patching, and it is used in downstream project for that purpose.