Retire stale support for interactive grid jobs with VNC access (#524)

* Retire the legacy interactive grid jobs using VNC and X-forwarding to the
resource running the job.
Also removes the stale vnc password handling being flagged in code scans.
Removes the 'interactive' jobtype in mRSL, resconfs and MiGserver.conf files.

The remaining occurrences of 'interactive' in `jobstatus.py` relate to the display
of various job management links and is unrelated AFAICT.
Similarly the ones in `liveio.py` only refer to operations that communicate with
running (batch) jobs.

* Remove vnc and interactive references outside actual code to make unit
tests pass

Author: jonasbardino

.gitignore

@@ -131,7 +131,6 @@ state/mig_system_files/*.sendupdatefiles
 state/mig_system_files/*.getoutputfiles
 state/mig_system_files/*.sendoutputfiles
 state/mig_system_files/*.job
-state/mig_system_files/*.interactivejob
 state/mig_system_run/*
 
 mig/install/generated-confs*
@@ -151,7 +150,6 @@ state/vgrid_files_readonly/*
 state/vgrid_public_base/*
 state/vgrid_private_base/*
 state/wwwpublic/vgrid/*
-state/wwwpublic/vnc/*
 state/sharelink_home/*
 state/freeze_home/*
 state/events_home/*