Support autoconverted modules in mixed builds

modules converted with bp2build_available are will also be available to
be used in mixed builds.

Test: build/bazel/scripts/milestone-2/demo.sh full
Test: go tests
Change-Id: I49f16ec3ba5bb11dfed8066af069c27eb04371fb
diff --git a/bp2build/build_conversion.go b/bp2build/build_conversion.go
index 962f278..9c98c76 100644
--- a/bp2build/build_conversion.go
+++ b/bp2build/build_conversion.go
@@ -235,7 +235,7 @@
 }
 
 func getBazelPackagePath(b android.Bazelable) string {
-	label := b.GetBazelLabel()
+	label := b.HandcraftedLabel()
 	pathToBuildFile := strings.TrimPrefix(label, "//")
 	pathToBuildFile = strings.Split(pathToBuildFile, ":")[0]
 	return pathToBuildFile