Move some prebuilt build tool configs to Soong

Now that they're defined with prebuilt_build_tool, we don't need to set
them here.

In future changes we can replace more of these definitions with
prebuilt_build_tool, as it can centralize the selection of
build-from-source or prebuilt for Make, Soong, and user-defined
genrules.

Test: treehugger
Change-Id: I4bb526492ebc6270b6030913c1f5b3f49dc61284