16909 - Tests spam console with sh: rpm: not found on Debian

When running tests on Debian the RpmpackagePackager tests spam the
console with rpm “sh: rpm: not found”.

RpmpackagePackager has had its shell commands moved to methods which are
now stubbed out in the debian tests.
16909 - Tests spam console with sh: rpm: not found on Debian

The previous commit for this ticket dit not correctly remove the console
spam when running tests on debian.

This commit removes the 'rpm not found' spam when running tests on
debian.