apiserver: Remove the deprecated `--experimental-encryption-provider-config` flag
apiserver: Remove the deprecated `--experimental-encryption-provider-config` flag

Signed-off-by: ialidzhikov <i.alidjikov@gmail.com>

Kubernetes-commit: 244bf1bd69c962041ba5cabc3c9e92f3f94a3ba4

kubernetes/apiserver,kubernetes/apiserver