Evaluate the need for selftests/run

[beraldoleal]

Currently our main entry point for checks is check.py. However selftests/run is called by selftests/run_coverage. We need to double check if that is really needed.

IIRC @willianrampazzo was working in somehow integrate avocado using the coverage' API, so maybe after that we can remove this file.

[clebergnu]

This is indeed related to https://github.com/avocado-framework/avocado/issues/4957