Limit interpolated axis values to set of valid values

Rouding the axis values to the nearest valid step value should keep the
var cache from missing repeatedly due to functionally identical axis
values. Formerly this was not a problem because the progress float was
rounded to the nearest animation frame. However that is no longer
occuring as it caused issues w/ non-linear interpolation.

Since different axes have different min and max values, we manually
adjust the step size to roughly target the same number of valid values
within that range. This gives us a good target, but also allows us to
make specific adjustments to keep hit-rate high depending on which
axes are more important visually.

Bug: 394840414
Test: Ran animation on device
Flag: NONE TextAnimator Memory Fix
Change-Id: I1800b71601ef10e1c2b9fd083134f312c8dd6711