ref(runtime-config): remove use_readthrough_query_cache (#7541)

More runtime config clean up

Author: MeredithAnya

tests/conftest.py

@@ -315,9 +315,3 @@ def set_config(key: str, value: Any) -> None:
         state.set_config(key, value)
 
     return set_config
-
-
-@pytest.fixture
-def disable_query_cache(snuba_set_config: SnubaSetConfig, redis_db: None) -> None:
-    snuba_set_config("use_cache", False)
-    snuba_set_config("use_readthrough_query_cache", 0)