Update database_load_balancing.md db replication steps

What does this Merge Request do and why?

This MR updates db replication preparation steps because the order of execution seems to be incorrect. With current revision when I run make postgresql-replication-primary I get an error:

➜  gdk git:(main) ✗ make postgresql-replication-primary
/bin/bash: /../gdk/postgresql-replica/data/pg_hba.conf: No such file or directory
make: *** [postgresql-replication/access] Error 1

However, if I run make postgresql-replication/data first then make postgresql-replication-primary works as expected, since there is an expectation to have postgresql-replica directory to be present, but make postgresql-replication-primary doesn't create it.

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 Issue to follow-up.
• Documentation added/updated, if needed.
• gdk doctor test added, if needed.
• Add the ~highlight label if this MR should be included in the CHANGELOG.md.