Problem/Motivation
On migration from D7, the taxonomy term fields get migrated fine, but they are set to allow all vocabularies, even though that wasn't the case in source.
Proposed resolution
In D7, the allowed vocabularies is a part of field settings which is not available in instance migration, which is where it needs to be in D8. We should add the settings first and then process it during migration.
Remaining tasks
Patch, review, commit.
User interface changes
None
API changes
None
Data model changes
None