Turn the init container back on

Summary

As part of #90 (closed) the init container was turned off. After we have native sidecars that will be implemented as part of gitlab#215 (closed) we can, and should, turn it back on.

Steps to reproduce

When deploying mattermost see if the init container comes up or not when hardening is enabled.

What is the current behavior?

The init container doesn't come up.

What is the expected behavior?

The init container should come up.

Relevant logs and/or screenshots

n/a

Possible fixes

Revert some of the work from the MR in #90 (closed) .