Turn off automatic reindexing by default, but reindex if no index is present yet.

[mgruner]

Which issue this PR fixes

• fixes #319

Special notes for your reviewer

• This does not introduce new variables, but changes default behaviour: Reindexing is not always forced now, but it happens when no index is present. This should be what most users want. It can be turned off via zammadConfig.elasticsearch.initalization = false
• Therefore I hope that a minor release is enough.

Checklist

• [x] Chart Version bumped

[mgruner]

@klml what do you think about this one? I hope we could do this without a major release.

[klml]

@mgruner I'm fine with it as long as I can suppress the reindex during deploy ;)