Revert "split function in search query FehlerkatalogsController"

This reverts commit 6c5a97de62516f98813b7c4c802de4f5b0a5549f.
Revert "Revert "split function in search query FehlerkatalogsController""

This reverts commit dbb01d398499875efd15ad1ab4eac902a73078aa.
redirect after deleting Pruefungsfehler back to prufungsgehler/index:id