Make PostgreSQL 14 as the default

What does this merge request do and why?

⚠ This needs gitlab!127178 (merged) to be merged first.

ℹ️ Once this MR is merged, and when you run gdk update, the support/upgrade-postgresql script will be executed.

This MR makes the PostgreSQL 14 as the default version in GDK.

In addition, the secondary database upgrade is now included in the support/upgrade-postgresql script if the user enables PostgreSQL replica in their GDK.

⚠️  WARNING: We're about to remove the old 'replica' database data because we will be replacing it with the primary database data.
Are you sure? [y/N]: y
ℹ️  Removing the old secondary database data...
ℹ️  Copying data from primary to secondary...

Closes #1831 (closed)

How to set up and validate locally

1. git checkout 1831-prefer-postgresql-14
2. gdk config set gitlab.default_branch "nh/prefer-postgresql-14" && gdk reconfigure
3. make update

The upgrade to PostgreSQL 14 and DB migration should be successful.

(Optional): If you enabled PostgreSQL replica (you can check using gdk config get postgresql.replica.enabled), the secondary database will also be automatically upgraded, and the postgresql-replica service should not have any errors.

Impacted categories

The following categories relate to this merge request:

• gdk-reliability - e.g. When a GDK action fails to complete.
• gdk-usability - e.g. Improvements or suggestions around how the GDK functions.
• gdk-performance - e.g. When a GDK action is slow or times out.

Merge request checklist

• This change is backward compatible. If not, please include steps to communicate to our users.
• Tests added for new functionality. If not, please raise an issue to follow-up.
• Documentation added/updated, if needed.
• Announcement added, if change is notable.
• gdk doctor test added, if needed.
• Add the ~highlight label if this MR should be included in the CHANGELOG.md.