Include Postgres-backed analytics in default deployment

[dabeeeenster]

The default helm chart should run with postgres backed analytics by default.

[JamesHarrison]

Given this is a very old and untouched issue, I'll +1 this but also add that if it isn't part of the default deployment, there is no mechanism (presently) to securely provide the DB connection URI from an existing secret, as with the databaseExternal options.

[matthewelwell]

@JamesHarrison acknowledging your comment, but we'll need to review the logic here before we can get back to you with more detail. Watch this space.

[khvn26]

This issue will be solved when #133 is merged. We need to update the new documentation in #133 to point users to the migration job introduced in #230.