Fork isolation scopes for event listeners in `@nestjs/bullmq`

[https://docs.nestjs.com/techniques/queues#event-listeners](<https://docs.nestjs.com/techniques/queues#event-listeners>)

We will soon have instrumentation for `@Processor` decorated classes with isolation context, tracing and error capturing for the `process` method. However, the issue still persists for event listeners which run in a separate context so we still need to fix that.