For some unknown reason the mock in this test leaks into the outside tests.
I wasn't able to determine why in the reasonable amount of time, so instead just
simplifying it to not use mocker at all.
That whole file should really be migrated to dvc-data, but that needs some time.
We used to have it named `cache` before, but these days it is clear that
you can have three odbs: just odb (e.g. in-memory), cache (typically local)
or remote (typically cloud). Fixing naming here before proceeding with
introducing `out.odb` and `out.cache`.
In preparation for migration to https://github.com/iterative/dvc-data/pull/304
Ruslan Kuprieiev
Peter Rowlands
Saugat Pachhai (सौगात)