Feature: Rename ddm_quota to dm_weight for disk RSEs too

[haozturk]

Feature Description

We're renaming this RSE attribute for tape RSEs at #728 We should do the same for disk as well. Before this is deployed, all stakeholders which use this attribute should be noticed: CRAB, WMCore at the very least

Use Case

It's confusing. It's used as a weight in the system, not as a quota.

Possible Solution

1. Update & rename the script
2. Inform the stakeholders
3. Deploy

Related Issues

#727