This patch configures the longhorn backup storage for longhorn. It's a
first run until the proper backup storage is complete.

This patch renames all uses of `Containerfile` with `Dockerfile` in
order to enable renovate to manage dependencies and images properly.
Currently renovate doesn't support the Containerfile name as match for
its docker module, which would mean that either there is custom config
added or renaming the files. Since there is no explicit benefit of using
Containerfile as name, this patch just renames them in order to avoid
custom renovate config.

Turns out there are unexpected structural changes in this upgrade that
we need to address separately.

It requires to deploy a CR after successful deployment, which means
we'll have to move the helm chart to bootstrape of work around this in
another way.

This patch adds the missing capability to install CRDs as part of the
metallb deployement.

This patch removes the component label, which was previously manually
added by our deployment, but is now part of the helm chart.

Due to a copy-paste mistake, dovecot was using the postfix replicaCount
for its own. This is obviously not intended and was fixed by this
commit, correcting the snapshot and adding obviously needed tests to
prevent such a mistake in the future.

This patch deployes the fixed postfix image containg postscreen with
enabled smtpd.

This patch creates a PDB for postfix, if the setup is scaled to more
than 1 postfix replica. This way at least one postfix instance should
always be available and the MTA therefore HA.

Currently the dovecot backend is not yet HA, this should take place
later on.

Currently each update of the application version requires an update of
the snapshot, this is annoying and doesn't help the chart with anything.
Therefore this patch enforces a chart version for all snapshot tests and
also stablizes the config reload hash magic regarding versioning
changes.