Fix missing gitlab-geo.conf when initiating replication

What does this MR do?

In !4495 (merged), we updated gitlab-ctl replicate-geo-database to support changes to replication settings introduced by PostgreSQL 12.

However, the gitlab-geo.conf file that was created when a secondary is configured, would be erased when initiating replication, as that file does not exist on the primary. Further, because we had removed the open mode from File.open, the file was not created when it didn't exist. This results in an error when running gitlab-ctl replicate-geo-database with Postgres 12.

This MR creates and writes gitlab-geo.conf from replicate-geo-database and removes creation of the file from the recipe as that is not needed until replication is initiated.

Related issues

Checklist

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Expected (please provide an explanation if not completing)

• Test plan indicating conditions for success has been posted and passes
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