Auto Deploy: disable `POSTGRES_ENABLED` by default

Auto Deploy: disable POSTGRES_ENABLED by default

Proposal

Change the default value of POSTGRES_ENABLED to have it disabled by default.

The Postgres chart used is not and is not meant to be production-ready. Still, some users started to rely on it extensively and that causes a maintenance burden for us and features that we never wanted to develop (like DB upgrades). By disabling Postgres by default, we can educate the users to look for a production-ready offering before they start using this feature.

Issue readiness checklist

• This issue/epic is shared with the team at a team meeting
• The proposal clearly states what is being deprecated, mentioning potentially related areas and features that are not affected
• The (in-product) communication plan about the removal is described in the proposal
• The documentation requirements of the removal are described in the proposal
• A preliminary timeline for the deprecation and removal is described in the proposal
• Deprecation message added to the deprecations.md file: !108653 (merged)
• Deprecation message posted in the release blog post: !117972 (merged)
• Deprecated code removed in %16.0: !117980 (merged)