Add E2E tests for async background tasks

[nicohrubec]

This should test that background tasks get proper isolation, so that e.g. breadcrumbs don't land on the global scope.

This should include:

• crons
• queues (@nestjs/bullmq, optionally nest-graphile-worker, we might also need special treatment for kafka/rabbitmq)
• @nestjs/event-emitter

[linear]

JS-1856

[nicohrubec]

I'll do this as part of the fixes actually.