Refactor getting replication updates from database v2. (#7740)

changelog.d/7740.misc

synapse/handlers/typing.py

synapse/replication/tcp/streams/_base.py

synapse/storage/data_stores/main/cache.py

synapse/storage/data_stores/main/deviceinbox.py

synapse/storage/data_stores/main/devices.py

synapse/storage/data_stores/main/end_to_end_keys.py

synapse/storage/data_stores/main/group_server.py

synapse/storage/data_stores/main/pusher.py

synapse/storage/data_stores/main/room.py

synapse/storage/data_stores/main/tags.py