xfs/161: adapt the test case for LBS filesystem

xfs/161: adapt the test case for LBS filesystem

This test fails for >= 64k filesystem block size on a 4k PAGE_SIZE
system(see LBS efforts[1]). Adapt the blksz so that we create more than
one block for the testcase.

Cap the blksz to be at least 64k to retain the same behaviour as before
for smaller filesystem blocksizes.

[1] LBS effort: https://lore.kernel.org/lkml/20230915183848.1018717-1-kernel@pankajraghav.com/

Signed-off-by: Pankaj Raghav <p.raghav@samsung.com>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Zorro Lang <zlang@redhat.com>
Signed-off-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Zorro Lang <zlang@kernel.org>