Move test results into TestResults directory (#35829)

Move test results into TestResults directory (#35829)

and avoid unique test results name as VSTest has issues with that.
Disabling capturing blame mode dumps at the moment until we have
cross-plat support for it.
Cleaning the results directory if the code coverage data collector is
used as there's currently not an easy way to distinguish between a new
and an old coverage results file. See tracking issue.