Skip old file cleanup for non-full builds.

There are few build targets that don't generate an installed file list,
e.g. product-graph. Skip the old installed file cleanup step so that the
func doesn't complain about a lack of the list file.

Fixes: 168105598
Test: m product-graph
Change-Id: Ib7dce6b801979bb565b74d6355143bac23b84fe6
diff --git a/ui/build/kati.go b/ui/build/kati.go
index 06ec646..668b20e 100644
--- a/ui/build/kati.go
+++ b/ui/build/kati.go
@@ -229,7 +229,11 @@
 
 	// Cleanup steps.
 	cleanCopyHeaders(ctx, config)
-	cleanOldInstalledFiles(ctx, config)
+	// Skip the old installed file cleanup step for few non-full build goals as we don't create
+	// an installed file list for them.
+	if config.FullBuild() {
+		cleanOldInstalledFiles(ctx, config)
+	}
 }
 
 // Clean out obsolete header files on the disk that were *not copied* during the