test: enable marking of failing coverage tests

Enable marking of coverage tests so that we can
allow some tests to fail without blocking the generation
of coverage data. This will later allow us to
fail the coverage job if other kinds of errors occur and
to capture which tests we believe are not running properly
with coverage enabled.

PR-URL: https://github.com/nodejs/node/pull/25671


Reviewed-By: Ben Coe <bencoe@gmail.com>
Reviewed-By: Ruben Bridgewater <ruben@bridgewater.de>
Reviewed-By: Refael Ackermann <refack@gmail.com>