Okapi path for fund code migration

Overview:

RestClient drops path of Okapi URL

Steps to Reproduce:

1. Configure an Okapi URL with path, for example https://example.com/okapi (learn details, https://folio-demo.gbv.de/ uses OkapiURL https://folio-demo.gbv.de/okapi)
2. Migrate to mod-orders-storage v12.0.1

Expected Results:

Migration succeeds.

Actual Results:

Migration fails with "Cross Migration for fund code synchronization failed".

Additional Information:

Note: This only affects a few installations that have a okapi url with path. Many use a separate host without a path component.