t/zbd: add run-tests-against-nullb script

t/zbd: add run-tests-against-nullb script

This script combines the t/zbd/run-tests-against-zoned-nullb script
functionality with t/zbd/run-tests-against-regular-nullb and adds
more zoned device configurations to test. This considerably improves
ZBD test coverage.

The added script makes the two old scripts named above obsolete,
remove them. Modify t/run-fio-tests.py and Makefile to refer to the
new script instead of the old one. Since the full test now runs
significantly longer than the two old ones combined due to many more
zoned configurations, only execute a few individual sections as a
part of testing n "make fulltest" and run-fio-tests.py. One extra test
section with 10% conventional zones is executed from the Makefile.
The Python tests only exercise all-conventional and all-sequential
configurations, exactly as before.

The script returns a non-zero return code if at least one of the
executed sections had a failed test.

Signed-off-by: Dmitry Fomichev <dmitry.fomichev@wdc.com>
Reviewed-by: Shin'ichiro Kawasaki <shinichiro.kawasaki@wdc.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>