Fix trace when remove address from trap/syslog source.

Fix trace when remove address from trap/syslog source.

Fix trace:

ERROR FINGERPRINT: 57e6ee85-3583-5365-8b21-ce530a6afb74
WORKING DIRECTORY: /opt/noc
EXCEPTION: <class 'KeyError'> '10.0.0.3'
START OF TRACEBACK
------------------------------------------------------------------------
File: services/trapcollector/service.py (Line: 153)
Function: update_source
  146             )
  147             new_addresses = set(cfg.addresses)
  148             # Add new addresses, update remaining
  149             for addr in new_addresses:
  150                 self.address_configs[addr] = cfg
  151             # Revoke stale addresses
  152             for addr in old_addresses - new_addresses:
  153 ==>             del self.address_configs[addr]
  154             # Update configs
  155             self.source_configs[data["id"]] = cfg
  156             # Update metrics
  157             metrics["sources_changed"] += 1
  158     
  159         async def delete_source(self, id):
Variables: