Fix color picker section showing no wallpaper color on build

Removed separate wallpaperColorOptions and presetColorOptions flows in
ColorPickerViewModel and combined into one. Because the original flows
both transformed the interactor colorOptions flow and both fed into the
final display options, they were making the flow run twice as many times
as needed on build. In addition, they were causing inconsistent
behaviors, like sometimes showing no color options on initial launch
after a build.

Bug: 269126622
Test: Manual, built and tested repeatedly to ensure wallpaper color
options consistently display in color section, tested with print
statements to observe the number of times a flow runs, ran
ColorPickerViewModelTest to ensure it still passes

Change-Id: I2bcb003b60c9a459967a41a9fb0d70b3ff110158