[backend] perlify BSNotify.pm a bit
[dist] unbreak lvm based startup again

Revert "[dist] Clean worker dirs on startup"

This reverts commit bac5c4559230c9d52cd49b11404682c45bf72b74.
[backend] disable async if testmode is set for now
[backend] add nofilename=1 to fill_remote_getrev_cache_projid