[3.0.1 Backport] Unable to upsert replication config username or password independently

In PR 4697, basic auth was added as config options in ISGR. In the Upsert function, an if statement was added to upsert the password field if the username is changed. This should actually upsert the password field if the password is changed.

This will need to be investigated to find the implications of this, repro the issue, and apply the fix.