Increase VolumeLog LogBuffer size.

Now both Volume Panel and Volume Dialog write to this buffer which makes
it easier to wash away the logs that might be relevant to the bugreport
investigation.

Flag: EXEMPT BUG_FIX
Fixes: 410590409
Test: passes presubmits
Change-Id: I58bf3d05a06b3b58b220856e0ca2e42002e7612d