replication: auto reconnect if password is invalid

Before the patch there was a race in replication
password configuration. It was possible that a replica
connects to a master with a custom password before
that password is actually set. The replica treated the
error as critical and exited.

But in fact it is not critical. Replica even can
withstand absence of a user and keeps reconnecting.
Wrong password situation arises from the same problem
of non atomic configuration and is fixed the same -
keep reconnect attempts if the password was wrong.

Closes #4550