Tests: Fix -direct variants of FetchContent tests using wrong files

The -direct variants of the RunCMake.FetchContent tests were
meant to be using the same result, stdout and stderr files as the
non-direct tests. The -direct tests were specified in the wrong way
for that and ended up using no files at all, so they weren't testing
the full set of expected conditions. Use the test variant feature
provided by the RunCMake infrastructure instead, which is the
proper way to handle this sort of scenario.
2 files changed