Use identity scale for filters_scale in RendererPixelTests

The filter scale and origin parameters to the RPDQ are used to directly
define the local matrix the image filters are evaluated with. Using a
default-constructed gfx::Vector2dF has a (0,0) scale factor so the
local matrix is the zero matrix and not invertible.

This went undetected previously because color filters don't have any
geometric parameters affected by the local matrix, so the zero matrix was being silently ignored. A skia-side change is making
`makeWithLocalMatrix()` return null if the matrix is not invertible,
so this updates the tests to use an identity value.

Bug: skia:9282
Bug: b/283467830
Change-Id: I82e9bcbf21c37b030127574b2c189abd292fe239
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/4595772
Reviewed-by: Kyle Charbonneau <kylechar@chromium.org>
Commit-Queue: Kyle Charbonneau <kylechar@chromium.org>
Auto-Submit: Michael Ludwig <michaelludwig@google.com>
Cr-Commit-Position: refs/heads/main@{#1154382}