productbuild: Simplify internal CPACK_PRODUCTBUILD_DOMAINS usage

There's no benefit to storing the CPACK_PRODUCTBUILD_DOMAINS
prefix in a variable and appending to it in the C++ code. It has the
disadvantage of making it harder to find usages of the variables with
a suffix appended to that string. Expand out the strings at the places
they are used so that they are easier to spot.
1 file changed