Improve script to find unused modules

[asdil12]

• Account for YAML scheduling
• Account commented out modules and actual loadtest

Ticket: https://progress.opensuse.org/issues/60908

[okurz]

not sure how it's supposed to work. E.g. I see in https://travis-ci.org/os-autoinst/os-autoinst-distri-opensuse/jobs/627265370#L539 that "yast2_gui/yast2_users" is reported as unused – at least this is how I interpret the output – but git grep 'yast2_users' shows that it's used in schedule/yast/yast2_gui.yaml

[asdil12]

Finally found the issue. It should work now.

[okurz]

Now the exclusion with the follow-up grep does not work anymore. https://travis-ci.org/os-autoinst/os-autoinst-distri-opensuse/jobs/627661649#L465 reports zypper_moo, which should be excluded, same as more others

[asdil12]

Now I made this whitelist which was very crude a bit more explicit so that it should work with the new code.
There are still some unused modules reported now that the old code did not detect.