[BUGFIX] IndexerService does not set creating user

When a backenduser uploads a file an index record is
created. The sys_file table ships with the column cruser_id
 which is never been filled because all sys_file records
are created by the IndexerService which does not take care
of that field.

Add this knowledge to the indexer service.

Releases: 6.0, 6.1
Fixes: #46596
Change-Id: I2a82ea5375b892604fc1a27376487bc4efe3a16e
Reviewed-on: https://review.typo3.org/19217
Reviewed-by: Wouter Wolters
Tested-by: Wouter Wolters
Reviewed-by: Stefan Neufeind
Reviewed-by: Andreas Wolf
Tested-by: Andreas Wolf