controllers/flights: Fixed datatable sorting
controllers/flights: Fixed datatable sorting

Sorting by pilot name has never worked since 'display_name' is not a column
of the flights table. The other sorting options were broken by the use of
joinedload() since the data is needed in the query for sorting.

Harry-R/skylines,kerel-fs/skylines,TobiasLohner/SkyLines,kerel-fs/skylines,RBE-Avionik/skylines,shadowoneau/skylines,shadowoneau/skylines,shadowoneau/skylines,snip/skylines,dkm/skylines,RBE-Avionik/skylines,Harry-R/skylines,dkm/skylines,skylines-project/skylines,skylines-project/skylines,Turbo87/skylines,skylines-project/skylines,RBE-Avionik/skylines,dkm/skylines,kerel-fs/skylines,Turbo87/skylines,skylines-project/skylines,TobiasLohner/SkyLines,Turbo87/skylines,snip/skylines,TobiasLohner/SkyLines,shadowoneau/skylines,snip/skylines,Harry-R/skylines,Harry-R/skylines,dkm/skylines,RBE-Avionik/skylines,Turbo87/skylines