KEP-3960: Introducing Sleep Action for PreStop Hook (kubernetes#3961)

* kep 3960

* remove Integration tests

* update user story

* update e2e test plan && risk

* add pr file & revert alpha to 1.28

* update Graduation Criteria

* add example

* no deprecations

* elaborate prr

* update prr

* fix nits

Author: AxeZhan

keps/prod-readiness/sig-node/3960.yaml

@@ -0,0 +1,6 @@
+# The KEP must have an approver from the
+# "prod-readiness-approvers" group
+# of http://git.k8s.io/enhancements/OWNERS_ALIASES
+kep-number: 3960
+alpha:
+  approver: "@wojtek-t"