Remove unused attributes from ResponseFuture class

These attributes are defined in ResponseFuture but never used:
- default_timeout: Only used in Session class
- _profile_manager: Only used in Session class
- _warned_timeout: Never referenced anywhere

Removing these attributes before adding __slots__ to ensure
clean slot definitions.

Signed-off-by: Yaniv Kaul <yaniv.kaul@scylladb.com>

Author: mykaul

cassandra/cluster.py

@@ -4316,10 +4316,8 @@ class ResponseFuture(object):
     session = None
     row_factory = None
     message = None
-    default_timeout = None
 
     _retry_policy = None
-    _profile_manager = None
 
     _req_id = None
     _final_result = _NOT_SET
@@ -4343,8 +4341,6 @@ class ResponseFuture(object):
     _continuous_paging_session = None
     _host = None
 
-    _warned_timeout = False
-
     def __init__(self, session, message, query, timeout, metrics=None, prepared_statement=None,
                  retry_policy=RetryPolicy(), row_factory=None, load_balancer=None, start_time=None,
                  speculative_execution_plan=None, continuous_paging_state=None, host=None):