Revert "build-and-provide-package: use -b for package builds that shouldn't include sources" [Closes: #88]

This reverts commit 649c70812e9ff22a0bb55f4719dff31d0c2e1e72.

The "-b" approach was just wrong when trying to fix:

| dh_virtualenv: error: no such option: -a

since any dh script should accept -a and -i.
Will follow up with a bug report against dh-virtualenv to
address the issue there.

Thanks: Christoph Berg <christoph.berg@credativ.de> for feedback