Update bezier_*_effects GMs to not use rand

It was disconcerting to have these change radically when I changed the code flow in another CL.

Change-Id: Ifd4c1be454e3f9291fa05f040545c95fa20be58a
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/255822
Reviewed-by: Greg Daniel <egdaniel@google.com>
Commit-Queue: Robert Phillips <robertphillips@google.com>
1 file changed