Don't hammer the database for destination retry timings every ~5mins (#10036)

changelog.d/10036.misc

synapse/app/generic_worker.py

synapse/federation/transport/server.py

synapse/replication/slave/storage/transactions.py

synapse/storage/databases/main/__init__.py

synapse/storage/databases/main/transactions.py

synapse/util/retryutils.py

tests/handlers/test_typing.py

tests/storage/test_transactions.py

tests/util/test_retryutils.py