Describe the bug
#1585 added the ability for each ensemble/nest to have its own diag/field/data yaml tables. However, in the default case where you are running with multiple ensembles and each ensemble is using the same diag/field/data yaml file, the code fails to find the correct yaml because it expects the *_table_ens_XX.yaml to be present and not just *_table.yaml

To Reproduce
This updated tests reproduce the behavior without the code updates

Expected behavior
Those test cases should work

System Environment
This happens in any system

Additional context
N/A