DR: Simplify the instructions to configure the primary server

Description

Right now, we have to go through to multiple steps to set up the primary server (documentation).

• sudo -u gitlab-psql /opt/gitlab/embedded/bin/psql -h /var/opt/gitlab/postgresql -d template1 -c "ALTER USER gitlab_replicator WITH ENCRYPTED PASSWORD 'thepassword'"
• Modify gitlab.rb and add the following

geo_primary_role['enable'] = true
postgresql['listen_address'] = "1.2.3.4"
postgresql['trust_auth_cidr_addresses'] = ['127.0.0.1/32','1.2.3.4/32']
postgresql['md5_auth_cidr_addresses'] = ['5.6.7.8/32']

Proposal

• Create a new command (gitlab-ctl setup-geo-primary) that will:
  • Automate the alteration of the gitlab_replicator user
  • Edit `gitlab.rb with
    • IP address of the primary detected automatically
    • IP address of the secondary as taken from the prompt below
  • Trigger a reconfigure automatically after processing the CLI

Indicate a password for the Postgre automated user who will replicate data between nodes
PROMPT
Indicate the IP address of the secondary node:
PROMPT
Do you want to add another secondary node? Y/N

This first command could be merged with the actual gitlab-ctl set-geo-primary-node required at this step.