As service_errors exclude all expected errors, for history service, ShardOwnershipLost can be expected during deployment. Why it not exclude from list for metric service_errors.
See your point, but think its ok that its included as it can give you possible indication of customer impact.
For example query you alert on can be service_errors_with_type
for operations StartWorkflowExecution|SignalWorkflowExecution|SignalWithStartWorkflowExecution
and you can exclude things by error type for example
error_type!="serviceerror.WorkflowExecutionAlreadyStarted"