Reduce applying empty transaction when finishing drawing

For example, when a snapshot starting window reports drawn, the
"t" will be null and mDrawHandlers is empty. But executeDrawHandlers
still invokes t.apply() which doesn't contain any operations.

Also reduce some unnecessary ArrayList creation by the way.

Bug: 442747045
Flag: EXEMPT refactor
Test: atest WindowStateTests#testApplyWithNextDraw
Change-Id: Ie082cb90f61406db99a31ca81ca70bf7c458fe2b