[BUGFIX] Label user function for sys_file_reference uses HTML

The change I7770044c11a6c1a1bcb51a3bfc11b85923653196 added meta
information for the FAL IRRE headers.
It uses a definition list to show certain fields of the related record
inside the title (thus visible if collapsed).
The HTML markup leads to problems in other places of the backend, most
noteable in the workspace module.

Introduce a separate user function only for inline labels,
using the same signature as the normal label_userFunc.

Resolves: #51411
Releases: 6.2
Change-Id: I070a9db3d009c743cb927be90a0aa3903a1bae45
Reviewed-on: https://review.typo3.org/23528
Reviewed-by: Markus Klein
Tested-by: Markus Klein
Reviewed-by: Georg Ringer
Tested-by: Georg Ringer