MINOR: server: ensure connection cleanup on server addr changes

MINOR: server: ensure connection cleanup on server addr changes

Previously, in srv_update_addr_port(), we forced connection cleanup on
server changes.
This was done in 6318d33ce ("BUG/MEDIUM: connections: force connections
cleanup on server changes").

However, there is no reason we shouldn't have done the same in
srv_update_addr() function, because the end goal is the same: perform
runtime changes on server's address.

The purge_conn hint propagated through the INETADDR server event was
simply there to keep the original behavior (only purge the connection
for events originating from srv_update_addr_port()), but to ensure the
address change is handled the same way for both code paths, we simply
ignore this hint.