* yaml: wrap ruamel's DuplicateKeyError
Unfortunately ruamel's exception doesn't contain much info that we could
reuse, so we can only reasonably extract the exc.problem and have
something like:
```
ERROR: failed to obtain data status - unable to read: 'dvc.yaml', found
duplicate key "metrics" with value "[]" (original value: "[]")
```
Fixes#4664
* status: remove unneeded error prefix