Merge pull request #3140 from matrix-org/rav/use_run_in_background

synapse/app/federation_sender.py

synapse/app/pusher.py

synapse/app/synchrotron.py

synapse/appservice/scheduler.py

synapse/crypto/keyring.py

synapse/federation/federation_client.py

synapse/groups/attestations.py

synapse/handlers/appservice.py

synapse/handlers/e2e_keys.py

synapse/handlers/federation.py

synapse/handlers/initial_sync.py

synapse/handlers/message.py

synapse/handlers/typing.py

synapse/push/pusherpool.py

synapse/rest/media/v1/preview_url_resource.py

synapse/storage/events_worker.py

synapse/storage/stream.py

synapse/util/async.py

synapse/util/file_consumer.py

synapse/util/logcontext.py