Deleting output globally which was added to multiple streams leaves stale references

[dennisoelkers]

Steps to reproduce:

1. Create two streams
2. Create output
3. Add to both streams
4. Delete Output globally

Result:

Managing the outputs of one of both streams will fail with a 500/NPE

This is due to the call which updates the streams collection not being flagged as multi update so it only removes the reference to the output of the first stream it finds.

[dennisoelkers]

Fixed in f83339d.