Rename HWUI memory atrace counters

"HWUI GPU Memory" feels like total GPU memory used by HWUI, but it's actually
the total of the memory categories not explictly listed. So this change renames
it to "HWUI Misc Memory".

Bug: 147833967
Test: take a systrace
Change-Id: Id6b5f09981e148373dbc4e7f482e3da35740a566