Automatic merge from submit-queue (batch tested with PRs 65301, 65291, 65307, 63845, 65313). If you want to cherry-pick this change to another branch, please follow the instructions <a href="https://github.com/kubernetes/community/blob/master/contributors/devel/cherry-picks.md">here</a>.

Add option to control SSL chain completion

**What this PR does / why we need it**:

This adds templated support to the kubernetes-worker juju charm for the --enable-ssl-chain-completion option on the ingress proxy.  It defaults to false, to ensure that production sites are not reliant on OCSP or DNS in order to function.

**Which issue(s) this PR fixes** *(optional, in `fixes #<issue number>(, fixes #<issue_number>, ...)` format, will close the issue(s) when PR gets merged)*:
Fixes #

**Special notes for your reviewer**:

**Release note**:

```release-note
kubernetes-worker juju charm: Added support for setting the --enable-ssl-chain-completion option on the ingress proxy.  "action required": if your installation relies on supplying incomplete certificate chains and using OCSP to fill them in, you must set "ingress-ssl-chain-completion" to "true" in your juju configuration.
```