Remove make-based unbundled file disting

Moving to soong for soong-only builds

Bug: 413145177
Test: TARGET_RELEASE=mainline_2025_07 TARGET_BUILD_VARIANT=userdebug PRODUCT=mainline_modules_x86_64 COVERAGE_MODULES=EXTSERVICES_TPLUS ./vendor/google/build/build_unbundled_coverage_mainline_module.sh -j64
Change-Id: If9c92348f65d6e1a3df3c67a4d0fb9fb4895a74e