Description of change
On the controller facades, creating cloud call context in the facade construction makes no sense since call context is model specific.
This PR changes the creation of the context to be in the actual facade call methods. All context creation has been moved to the calls that use context rather than forcing it to happen too early and for every call.
QA steps
steps in bug report do not result in the controller model cloud credential to be invalidated.
Bug reference
https://bugs.launchpad.net/juju/+bug/1848104
该提问来源于开源项目：juju/juju
