Fix EBS cleanup job typo

[achantavy]

Fix: changes EBS volume cleanup job from ATTACHED_TO => ATTACHED_TO_EC2_INSTANCE.

---

This is already annotated in docs here as ATTACHED_TO_EC2_INSTANCE: https://github.com/lyft/cartography/blob/master/docs/root/modules/aws/schema.md#relationships-69

and this is created in the code itself as ATTACHED_TO_EC2_INSTANCE:

cartography/cartography/intel/aws/ec2/volumes.py

Line 82 in 2903dbe

MERGE (volume)-[r:ATTACHED_TO_EC2_INSTANCE]->(instance)

So the cleanup job here is wrong.