Refresh_foreign_tables rake task was required during 12.4.x to 12.5.x Geo HA upgrade

During the 12.4.x to 12.5.x Geo HA upgrade, after running post-deployment db migrations on secondary deploy node and then running gitlab-ctl reconfigure, we still needed to run gitlab-rake geo:db:refresh_foreign_tables (as recommended by the output of gitlab-rake gitlab:geo:check). This step used to be in the instructions but was replaced by (1) waiting for primary migrations to finish/replicate, then (2) running gitlab-ctl reconfigure.

Let's investigate if this was user error and/or if the instructions should be modified.

cc @vsizov