This patch keeps the check for isWriteMode inside the EntitySavingHelper
instead of extracting it similar to what was done in
Ic6e9eb2717ac9f7ec8b7fb3d2dabaf5c3331592c. The rationale is that to
properly extract it we should probably create a EntitySavingHelper
interface and then have a WritingEntitySacingHelper and
NonWritingEntitySavingHelper implementing it in order to properly
separate those concerns. This amount of abstraction seems to not be
worth it for a mere safety check that is never expected to be triggered,
unless there is a bug somewhere.

Co-authored-by: Bereket teshome <bereket.teshome@wikimedia.de>
Bug: T277525
Change-Id: I4cb1c9e7e98c308be3e9c576da67d5f2514ae6f4