coverage: Also remove source_root prefixes
coverage: Also remove source_root prefixes

The code our projects care about verifying coverage for mostly lives in
the source_root with the exception of the generated source files in
build_root. This change cleans up the output so we don't have prefixed
paths on our source files anymore.

QuLogic/meson,QuLogic/meson,pexip/meson,mesonbuild/meson,jpakkane/meson,pexip/meson,jpakkane/meson,mesonbuild/meson,mesonbuild/meson,pexip/meson,mesonbuild/meson,QuLogic/meson,QuLogic/meson,QuLogic/meson,pexip/meson,jpakkane/meson,becm/meson,mesonbuild/meson,becm/meson,pexip/meson,jpakkane/meson,pexip/meson,pexip/meson,becm/meson,jpakkane/meson,becm/meson,mesonbuild/meson,jpakkane/meson,QuLogic/meson,jpakkane/meson,becm/meson,pexip/meson,QuLogic/meson,QuLogic/meson,pexip/meson,pexip/meson,becm/meson,becm/meson,mesonbuild/meson,becm/meson,mesonbuild/meson,jpakkane/meson,jpakkane/meson,mesonbuild/meson,QuLogic/meson,mesonbuild/meson,becm/meson,becm/meson