ZTS: Remove ashift setting from dedup_quota test (#17250)

The test writes 1M of 1KB blocks, which may produce up to 1GB of
dirty data. On top of that ashift=12 likely produces additional
4GB of ZIO buffers during sync process. On top of that we likely
need some page cache since the pool reside on files. And finally
we need to cache the DDT. Not surprising that the test regularly
ends up in OOMs, possibly depending on TXG size variations.

Also replace fio with pretty strange parameter set with a set of
dd writes and TXG commits, just as we neeed here.

While here, remove compression. It has nothing to do here, but
waste CI CPU time.

Signed-off-by: Alexander Motin <mav@FreeBSD.org>
Sponsored by: iXsystems, Inc.
Reviewed-by: Paul Dagnelie <pcd@delphix.com>
Reviewed-by: Tony Hutter <hutter2@llnl.gov>