Additionally remove coverage files before the run, because they're not
compatible with standard coverage results and could cause failures.
Change-Id: I5937ed1b04bda0741b41972808107829f589ec9e
Remove specific None check, since class check already covers it.
Don't require testing abstract methods in coverage.
Change-Id: I37aa3ed1fc7b4713851abf909e5c28f9d04eb1a9