mediav2: Limit Rect.isValid() to Android T and above

Bug: 332574755
Bug: 332469709
Test: Ensure there are no unexpected failures with the following on
Android R device.
atest CtsMediaV2TestCases:CodecEncoderSurfaceTest -- --module-arg\
CtsMediaV2TestCases:instrumentation-arg:codec-prefix:=c2.android.

Change-Id: I50f4bfe994c37f21a263def3e368b9d1883569e2