We always send traces that includes an error node if the trace has an
error. In the case that sending errors is disabled, we replace the
message and remove the location.

Note that the Engine proxy strips all error information from the traces
with noErrorTraces set. To get errors to show up in the ui, the proxy
sends error counts inside of the aggregated stats reports. To get
similar behavior inside of the apollo server metrics reporting, we
always send a trace and mask out the PII.