Fix multiproduct_kati product list

When the config loading was changed to using AndroidProducts.mk lists
from soong_ui instead of finding them itself, multiproduct_kati stopped
being able to find all the products. Move the finder initialization
earlier so that we can dump the full list.

Test: build/soong/build_test.bash -only-config
Test: forrest runs of every downstream build_test
Change-Id: I085d40f9008a47b850783499365977a0ff70ac66
diff --git a/cmd/multiproduct_kati/main.go b/cmd/multiproduct_kati/main.go
index 06c5626..ab82963 100644
--- a/cmd/multiproduct_kati/main.go
+++ b/cmd/multiproduct_kati/main.go
@@ -255,6 +255,11 @@
 
 	setMaxFiles(log)
 
+	finder := build.NewSourceFinder(buildCtx, config)
+	defer finder.Shutdown()
+
+	build.FindSources(buildCtx, config, finder)
+
 	vars, err := build.DumpMakeVars(buildCtx, config, nil, []string{"all_named_products"})
 	if err != nil {
 		log.Fatal(err)
@@ -303,9 +308,6 @@
 	var wg sync.WaitGroup
 	productConfigs := make(chan Product, len(products))
 
-	finder := build.NewSourceFinder(buildCtx, config)
-	defer finder.Shutdown()
-
 	// Run the product config for every product in parallel
 	for _, product := range products {
 		wg.Add(1)