This test is intended to check that DefaultLoadControl will cause
playback to fail as "stuck buffering" rather than OOM-ing, in the
case that its target buffer size is reached and playback still
hasn't started.
Unfortunately, the target buffer size is ~130MB, and when running
on some setups an OOM actually ends up happening before this much
memory is allocated.
This change makes the target buffer size much smaller to avoid the
problem.
PiperOrigin-RevId: 331748208
f387574140