memory: bug fix to not register twice frontends parameters + added some tests for param update

src/test/helpers.py

@@ -240,6 +240,7 @@ class FakeMemory(Memory):
         re-initialise the memory first to not fake the result."""
         self.params.load_default_params()
         self.params.params.clear()
+        self.params.frontends_cache = []
         self.entities_data = {}
         self.server_features = {}