mm/damon/tests/core-kunit: remove a redundant test case and add a new test case in...

mm/damon/tests/core-kunit: remove a redundant test case and add a new test case in damos_test_commit_quota_goal()

Remove a redundant test case from damos_test_commit_quota_goal() as it is
already covered.  Instead, add a new test for DAMOS_QUOTA_SOME_MEM_PSI_US,
which was previously not tested.

Link: https://lkml.kernel.org/r/20251224042200.2061847-6-shu17az@gmail.com
Signed-off-by: Shu Anzai <shu17az@gmail.com>
Reviewed-by: SeongJae Park <sj@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>