Fix target zip filename matching in assemble_cvd

Test: Create mixed build setup, scp in new assemble_cvd, run launch_cvd
Bug: 131697923
Change-Id: I30a0764ad63a872cee934abd2a6d3bb932ea7d53
diff --git a/host/commands/assemble_cvd/super_image_mixer.cc b/host/commands/assemble_cvd/super_image_mixer.cc
index fcc0dc1..78d2750 100644
--- a/host/commands/assemble_cvd/super_image_mixer.cc
+++ b/host/commands/assemble_cvd/super_image_mixer.cc
@@ -46,9 +46,8 @@
     }
     std::string expected_filename = "target_files-" + file_iter.second.build_id;
     if (file_path.find(expected_filename) != std::string::npos) {
-      continue;
+      return file_path;
     }
-    return file_path;;
   }
   return "";
 }