pool: Improve selection of listening address

Similar to https://rb.dcache.org/r/7598/, but applies the same optimisation
to dcap, http, nfs and xrootd movers.

Target: trunk
Require-notes: yes
Require-book: no
Acked-by: Tigran Mkrtchyan <tigran.mkrtchyan@desy.de>
Patch: 	https://rb.dcache.org/r/7599/