Fix ripple alpha.

During polishing, the default alpha value is changed to 1 in the
RippleShader. It should be .45 by default.

It might take more time to fix the refactor CL that contains this change, so created a separate CL for this. ag/19582192

Test: Manual - test Wireless, wired, and media ttt ripple animations manaully.
Bug: b/237282686
Change-Id: Ie82097bbf17dad8b888a2c706a76f16bc29529ed