This commit enables the parametrization for "legacy-combined" protocol.
All failing tests with that have been either fixed or disabled. Notably:
- A couple of tests (e.g. involving builders) could be made to work with
a non-local store, but this would require some refactoring to testlib in
order to make certain configuration settings generic over local and
remote operations. We've disabled those for now, in order to make
progress
- The store tests all run locally only because of their nature
- The flakes tests also all run locally only because my energy for
fixing them is limited (and it's a *lot* of test failures, with probably
little overall benefit in terms of test coverage)
Change-Id: I56fa249a64f7c17c952f688ec89e9687f2a13f12
