VC: ERR/WRN log spam when BN goes down

[arnetheduck]

When BN goes down, VC logs several error/warning messages per second due to various subcomponents failing independently - at most one ERR/WRN log per slot should be printed in this case.

WRN 2022-05-31 15:33:55.008+02:00 No working beacon nodes available, refreshing nodes status online_nodes=0 unusable_nodes=1 request=getHeadBlockRoot
ERR 2022-05-31 15:33:55.009+02:00 Unable to check beacon node's status       error_name=RestCommunicationError error_message="Communication failed while sending/receiving request, http error [HttpConnectionError]: Could not connect to remote host" endpoint="localhost:11101 [Nimbus/v22.5.1-85d023-stateofus]"
WRN 2022-05-31 15:33:55.018+02:00 No working beacon nodes available, refreshing nodes status online_nodes=0 unusable_nodes=1 request=getProposerDuties
ERR 2022-05-31 15:33:55.019+02:00 Unable to check beacon node's status       error_name=RestCommunicationError error_message="Communication failed while sending/receiving request, http error [HttpConnectionError]: Could not connect to remote host" endpoint="localhost:11101 [Nimbus/v22.5.1-85d023-stateofus]"
WRN 2022-05-31 15:33:55.053+02:00 No working beacon nodes available, refreshing nodes status online_nodes=0 unusable_nodes=1 request=getSyncCommitteeDuties
WRN 2022-05-31 15:33:55.053+02:00 No working beacon nodes available, refreshing nodes status online_nodes=0 unusable_nodes=1 request=getAttesterDuties
ERR 2022-05-31 15:33:55.054+02:00 Unable to check beacon node's status       error_name=RestCommunicationError error_message="Communication failed while sending/receiving request, http error [HttpConnectionError]: Could not connect to remote host" endpoint="localhost:11101 [Nimbus/v22.5.1-85d023-stateofus]"

Example with 7 errors within 50ms - 85d023452494b348033be85033317ebd22799980