aconfig: turn off the offending test point

Bug: b/324459233
Test: atest aconfig_storage_file.test and the test point is no longer executed.
Change-Id: I34b5da7a1b152f213926cc2e1f9511785e9d384f
diff --git a/tools/aconfig/aconfig_storage_file/src/mapped_file.rs b/tools/aconfig/aconfig_storage_file/src/mapped_file.rs
index ad0c66f..3929dbd 100644
--- a/tools/aconfig/aconfig_storage_file/src/mapped_file.rs
+++ b/tools/aconfig/aconfig_storage_file/src/mapped_file.rs
@@ -243,6 +243,7 @@
     }
 
     #[test]
+    #[cfg(feature = "cargo")]
     fn test_map_non_read_only_file() {
         #[cfg(feature = "cargo")]
         create_temp_storage_files_for_test();