Reduce memory churn in KawaseBlurFilter::generate

We may use up to 4 passes for generating the blur. Rather than
generating a new Surface (all of the same size) for each pass,
generate at most 2 surfaces and ping pong back and forth.

In addition, early exit if blurRadius is zero.

Bug: 290294055
Bug: 279894071
Bug: 275754150
Test: manual (pull down notification shade)
Test: atest BlurTests
Change-Id: I7ad2438a0e5d9e437b0256eb302fe2fd44e9c093