#4243 Other bulk write handlers may read a lost connection as every row written

From swamp-club#4204. createMany in mongo-notification-repository.ts treated a bulk error with an empty writeErrors list as success, so an outage returned 200 with nothing stored. The same shape appears at services/telemetry/lib/consumers/counter.ts (two sites), which checks only that writeErrors is present, and at lib/infrastructure/mongo-nurture-send-repository.ts, which defaults it to an empty list. These have not been driven through a failure. Expected: a bulk error with no per-row errors is treated as a failed write.