Wip/ritesh/fix devscripts ftbfs

The previous fix wasn't enough to get rid of libgitlab-api-v4-perl. This change also disables one of the tests, salsa.pl, from execution.

Other than that, devscripts was failing to build from source, in the Buster version. There is a patch, included upstream, which I have applied through this MR.

I have tested the package and it builds fine on my OBS home branch