Rspec no longer uses the spec.opts file, and this particular file also uses
options for rspec that are no longer honored or available, like loadby. So this
commit removes the file. Users that want to customize rspec behavior should use
a .rspec file in the repository root or in their home directory.
This commit adds test coverage for apt::ppa.
This test coverage is suficient to verify the
code changes that resolve the issue with
aptitude update not being called when ppas were
added (#10451).