Remove unused functions from synapse/storage/signatures.py
Remove unused functions from synapse/storage/signatures.py

iot-factory/synapse,matrix-org/synapse,matrix-org/synapse,iot-factory/synapse,matrix-org/synapse,iot-factory/synapse,matrix-org/synapse,iot-factory/synapse,TribeMedia/synapse,matrix-org/synapse,iot-factory/synapse,TribeMedia/synapse,matrix-org/synapse,TribeMedia/synapse,TribeMedia/synapse,TribeMedia/synapse