Holdings cannot be exported with custom mapping profile

Overview:
In addition to the default mapping profile, users should be able to create a custom mapping profile where any supported holdings field can be included.

Steps to Reproduce:
1. Navigate to Settings->Data export -> Mapping profiles
2. Build a mapping profile that includes only holdings record type and the following transformations:

3. Navigate to the job profiles, create a new one and associate it with the mapping profile from the previous step
4. Trigger the export using this profile

Expected Results:
.mrc file is generated and contains all fields as specified in the mapping profile populated with the data from inventory instance record

Actual Results:
The export fails with "For exporting holding records only the default holding job profile is supported"
Additional Information:
Example from Nolana bugfest:

https://bugfest-nolana.int.aws.folio.org/data-export/log/4e59f2c2-47c3-4175-8b68-f04f68f0daf8