Remove all bazel related files in skia, cause Skia

is still in migrating to Bazel and unable to handle
it's transitive deps.

prepare.sh

@@ -17,7 +17,7 @@ fi
 
 cd $SKIA_PATH
 
-builds=$(find . | grep bazel | xargs)
+builds=$(find . | grep -e "[^.]*\.bazel$")
 if [ ! -z "$builds" ]; then
    rm $builds
 fi