SystemStore migration to return plain errors (#14835)

* SystemStore migration to return plain errors

* Fix nilness

* Fix translations

* Fix merge

* Fix layers

* Fix merge errors

* Lint: remove unnecessary use of sprint

* Fix merge errors

* Fix i18n

Co-authored-by: Agniva De Sarker <agnivade@yahoo.co.in>

store/store.go

@@ -429,13 +429,13 @@ type OAuthStore interface {
 }
 
 type SystemStore interface {
-	Save(system *model.System) *model.AppError
-	SaveOrUpdate(system *model.System) *model.AppError
-	Update(system *model.System) *model.AppError
-	Get() (model.StringMap, *model.AppError)
-	GetByName(name string) (*model.System, *model.AppError)
-	PermanentDeleteByName(name string) (*model.System, *model.AppError)
-	InsertIfExists(system *model.System) (*model.System, *model.AppError)
+	Save(system *model.System) error
+	SaveOrUpdate(system *model.System) error
+	Update(system *model.System) error
+	Get() (model.StringMap, error)
+	GetByName(name string) (*model.System, error)
+	PermanentDeleteByName(name string) (*model.System, error)
+	InsertIfExists(system *model.System) (*model.System, error)
 }
 
 type WebhookStore interface {