Fixes pause/resume failure on w/lib & x/mit lp:1570375

Pause failed as configure_https() had a service restart that was missed
in the initial pause/resume feature addition.  configure_https() was
triggered via a 'config-changed' hook that could occur whilst the unit
is pause.

Also enhanced the pause/resume test to include a forced 'config-changed'
hook to run to test that the fix works.

Change-Id: I0d2820fe5d447dd7877afacb0a63a8590f027b31
Closes-Bug: #1570375