Remove deprecated kubectl --dry-run values.
Remove deprecated kubectl --dry-run values.

The boolean values for --dry-run have been deprecated for removal since
1.18, more than 2 releases.

The default value for --dry-run with the flag set and unspecified has
been deprecated for removal since 1.18, more than 2 releases.

Both values are now removed in this change. Any kubectl --dry-run
usage no longer accepts --dry-run=(true|false) boolean values and usage
now requires that a value of (client|server|none) is specified.

Kubernetes-commit: e0b7a85ee5b5d546bec2dc0e8cbf5cd4c0c684d8

kubernetes/kubectl,kubernetes/kubectl