common/dmlogwrites: add _require_log_writes_sized helper

Add a new helper function _require_log_writes_sized() to check if the
LOGWRITES_DEV meets a minimum size requirement.

This is useful for tests that use dm-log-writes with additional space
requirements, such as creating LVM snapshots during log replay or tests
that generate large amounts of logged I/O operations.

The function takes a size parameter in KB, calls _require_log_writes()
internally, and skips the test if LOGWRITES_DEV is smaller than the
required size.

Suggested-by: Darrick J. Wong <djwong@kernel.org>
Suggested-by: Anand Jain <anajain.sg@gmail.com>
Signed-off-by: Disha Goel <disgoel@linux.ibm.com>
Reviewed-by: Zorro Lang <zlang@kernel.org>
Signed-off-by: Zorro Lang <zlang@kernel.org>