fuzzer testsuite tests are not run due to a missing subclass method '_should_filter_by_name' in fuzzer/testcfg.py

This CL fixes the filtering for the 'fuzzer' testsuite

R=machenbach@chromium.org

Bug: v8:10770
Change-Id: I9a4b0e0c6c79f4b525ee284df343acccc965f732
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2336802
Auto-Submit: Tamer Tas <tmrts@chromium.org>
Commit-Queue: Michael Achenbach <machenbach@chromium.org>
Reviewed-by: Michael Achenbach <machenbach@chromium.org>
Cr-Commit-Position: refs/heads/master@{#69235}