Use the proper mock test for the ComputationalResourceWidget

[unkcpz]

#601 fix a critical bug but I find it is not easy to find where to add the proper test.
There are two types of tests for the ComputationalResourceWidget, one is the database are fully made up for the test of template widget, and the other is directly test against the database fetched from https://aiidateam.github.io/aiida-resource-registry/database.json.
For the second one, it would be more proper to fetch it locally as a copy mock to synchronize with the remote to reproduce the issues and test the fix.