[BUGFIX] IRRE records are listed comma separated

IRRE records with foreign_field instead of MM table
are now listed as a comma separated list instead
of wrongly using the number of records as the UID.

Change-Id: Ib1434561ee823d931cc983e103fb58490ca83719
Resolves: #59671
Releases: 6.3,6.2
Reviewed-on: https://review.typo3.org/31281
Reviewed-by: Wouter Wolters
Tested-by: Wouter Wolters