Ceph default port for https console

It might help others to set the default Ceph console https port from 8443 to something unused/standard? Otherwise the LXD console and Ceph console conflict on that port. Not certain if it should be in docs or just set in the background so enablement "just works". I used `sudo microceph.ceph config set mgr mgr/dashboard/ssl_server_port 6443` since 7443 seems to also be used.

Review how enablement sets Ceph's mgr/dashboard/ssl_server_port and how the LXD console selects its port; the issue reports an 8443 conflict and a manual 6443 workaround. Done means deciding whether enablement should choose a non-conflicting default or documenting the required configuration.

Written by the indexing model from the issue text.