Unify with the rest of application destroy method in questions controller

We also add a missing translation.

app/controllers/admin/poll/questions_controller.rb

@@ -43,12 +43,8 @@ class Admin::Poll::QuestionsController < Admin::Poll::BaseController
   end
 
   def destroy
-    if @question.destroy
-      notice = "Question destroyed succesfully"
-    else
-      notice = t("flash.actions.destroy.error")
-    end
-    redirect_to admin_poll_path(@question.poll), notice: notice
+    @question.destroy!
+    redirect_to admin_poll_path(@question.poll), notice: t("admin.questions.destroy.notice")
   end
 
   private

config/locales/en/admin.yml

@@ -1126,6 +1126,8 @@ en:
       new:
         title: "Create question to poll %{poll}"
         title_proposal: "Create question"
+      destroy:
+        notice: "Question deleted succesfully"
       answers:
         images:
           add_image: "Add image"

config/locales/es/admin.yml

@@ -1125,6 +1125,8 @@ es:
       new:
         title: "Crear pregunta ciudadana para la votación %{poll}"
         title_proposal: "Crear pregunta ciudadana"
+      destroy:
+        notice: "Pregunta eliminada correctamente"
       answers:
         images:
           add_image: "Añadir imagen"