fix: init pod run perms

[rhdedgar]

Setting FSGroup to convey the need for a more permissive scc.

Closes RHAIENG-999.

[rhdedgar]

It's possible the RunAsUser setting could even be removed in the future, as the FSGroup: 0 setting should provide the necessary volume access.

[derekhiggins]

So we're dropping some privileges from the init container while mounting storage in as the 'root' group so that containers can always write to volumes?

Would you mind putting a little context on why this is needed in here (as not everybody can see what RHAIENG-999 is )

[rhdedgar]

Sure! So from the ticket, setting storage to something like:

    storage:
      size: 10Gi

Can cause the permissions error:
forbidden: unable to validate against any security context constraint

I was able to replicate that error on an OpenShift 4.18 cluster.

I've updated the FSGroup to match the container's existing RunAsUser and RunAsGroup settings to address that security discrepancy.

I also dropped the additional unneeded capabilities that would normally be given to pods that aren't run as restricted-v2, so that this fix doesn't grant more than it needs to.

[derekhiggins]

Thanks