MINOR: server: ensure server postparse tasks are run for dynamic servers

MINOR: server: ensure server postparse tasks are run for dynamic servers

commit 29b76cae4 ("BUG/MEDIUM: server/log: "mode log" after server
keyword causes crash") introduced some postparsing checks/tasks for
server

Initially they were mainly meant for "mode log" servers postparsing, but
we already have a check dedicated to "tcp/http" servers (ie: only tcp
proto supported)

However when dynamic servers are added they bypass _srv_postparse() since
the REGISTER_POST_SERVER_CHECK() is only executed for servers defined in
the configuration.

To ensure consistency between dynamic and static servers, and ensure no
post-check init routine is missed, let's manually invoke _srv_postparse()
after creating a dynamic server added via the cli.