Is your feature request related to a problem? Please describe.
By convention, class color customization addons like Class Colors often utilize a CUSTOM_CLASS_COLORS table to work around taint from modifying RAID_CLASS_COLOR directly.

The expectation is for others addons to be able to easily support a user's color preference via this table, ultimately giving the user a consistent set of class colors across all their addons/blizz ui elements.

Describe the solution you'd like
Could likely just redefine RAID_CLASS_COLOR at the top of any file thats using it.

local RAID_CLASS_COLOR = RAID_CLASS_COLORS
if CUSTOM_CLASS_COLORS then
  -- fill any missing classes
  for class, baseColor in pairs(RAID_CLASS_COLORS) do
    if not CUSTOM_CLASS_COLORS[class] then
      CUSTOM_CLASS_COLORS[class] = baseColor
    end
  end
  RAID_CLASS_COLORS = CUSTOM_CLASS_COLORS
end

Additional Context
related issue - https://legacy.curseforge.com/wow/addons/lfg-group-finder-bulletin-board/?comment=600