Include test_os.sh in GlideinWMS
test_os.sh is a script used in Factories.
It is currently hosted and maintained outside GWMS.
Since it seems used in all Factories and problems have been recurring problems due to its upkeep, this should be included in GWMS.
- find the authoritative copy of the script
- include it in creation/web-base
- update it to include rhel/centos 7 and 8 support
- add other updates (check condor_platform_select.sh)
- consider factoring out common code between the 2