docker: fix the tito command for building packages without running tests
There are two ways to build a package without running tests:
1) Using --rpmbuild-options='--without=check'
which is currently in our Dockerfiles. The problem here is, that
the spec file needs to support it, e.g.
%check
%if %{with check}
./run_tests.sh
%endif
Not all of our packages do this. For example copr-backend doesn't.
2) Using --rpmbuild-options='--nocheck'
which works in all cases. Therefore, I switching to it.
Merges: #1053