[FIX] Tests: Actually do dry site tests

Because the metaclass didn't check if 'dry' was selected via a subclass
those tests weren't done at all with nose. This sets 'dry' then and also fixes
all tests which implicitly loaded the site and thus failed.

Bug: 72885
Change-Id: I7010d45d2e99f123528465bbc236e7e08fdc721d
Merge "[FIX] Tests: Actually do dry site tests"