cached_traffic_control: fix regression tests

Avoid using shared memory in tests because of permission problems.

src/cached_traffic_control.rs

@@ -348,6 +348,7 @@ rule: somewhere
 
         let mut cache = TrafficControlCache::new();
         cache.use_utc = true;
+        cache.use_shared_memory = false; // avoid permission problems in test environment
 
         cache.update_config(&config)?;