xfs/17[013]: fix intermittent failures when filesystem metadata gets large

xfs/17[013]: fix intermittent failures when filesystem metadata gets large

These tests check that the filestreams allocator never shares an AG
across multiple streams when there's plenty of space in the filesystem.
Recent increases in metadata overhead for newer features (e.g. bigger
logs due to reflink) can throw this off, so add another AG to the
formatted filesystem to encourage it to avoid the AG with the log.

Signed-off-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Zorro Lang <zlang@redhat.com>
Signed-off-by: Eryu Guan <guaneryu@gmail.com>