Copy customization of main (parent) server in management context

If the actuator endpoints are configured on a different port then there
are some settings in the main ServerProperties that we would like to
re-use (e.g. the access log). The easiest way to do that is to just
configure the management server using the same ServerProperties instance
and then overwrite the things that are different (and stored in
ManagementServerProperties).

Fixes gh-1581