fix git-annex test -p

fix git-annex test -p

test: When limiting tests to run with -p, work around tasty limitation by
automatically including dependent tests.

This fixes a reversion because it didn't used to use dependencies and
forced tasty to run the init tests first. That changed when parallelizing
the test suite.

It will sometimes do a little more work than strictly required,
because it adds init tests deps when limited to eg quickcheck tests,
which don't depend on them. But this only adds a few seconds work.

Sponsored-by: Dartmouth College's Datalad project