Fix MediaCas claimResource logic

When a resource is claimed by a resource challenger, and there is only 1
resource available, the check in claimResource that the CAS is fully
used is incorrect. The challenger "challenges" for a resource from the
CAS only if the CAS was fully used and if the challenger wins, then the
CAS will continue to be fully used. Removing this check.

Bug: 381864924
Flag: EXEMPT bugfix
Test: atest android.media.misc.cts.MediaCasTest
Change-Id: I51cd5c2f8f939ffdb504b9043a22bc06c07985cc