models: remove belongs_to_creator macro.

The belongs_to_creator macro was used to initialize the creator_id field
to the CurrentUser. This made tests complicated because it meant you had
to create and set the current user every time you wanted to create an
object, when lead to the current user being set over and over again. It
also meant you had to constantly be aware of what the CurrentUser was in
many different contexts, which was often confusing. Setting creators
explicitly simplifies everything greatly.

test/functional/bulk_update_requests_controller_test.rb

@@ -5,6 +5,7 @@ class BulkUpdateRequestsControllerTest < ActionDispatch::IntegrationTest
     setup do
       @user = create(:user)
       @admin = create(:admin_user)
+      @bulk_update_request = create(:bulk_update_request, user: @user)
     end
 
     context "#new" do
@@ -23,12 +24,6 @@ class BulkUpdateRequestsControllerTest < ActionDispatch::IntegrationTest
     end
 
     context "#update" do
-      setup do
-        as_user do
-          @bulk_update_request = create(:bulk_update_request)
-        end
-      end
-
       should "still handle enabled secondary validations correctly" do
         put_auth bulk_update_request_path(@bulk_update_request.id), @user, params: {bulk_update_request: {script: "create alias zzz -> 222", skip_secondary_validations: "0"}}
         @bulk_update_request.reload
@@ -43,12 +38,6 @@ class BulkUpdateRequestsControllerTest < ActionDispatch::IntegrationTest
     end
 
     context "#index" do
-      setup do
-        as_user do
-          @bulk_update_request = create(:bulk_update_request)
-        end
-      end
-
       should "render" do
         get bulk_update_requests_path
         assert_response :success
@@ -56,12 +45,6 @@ class BulkUpdateRequestsControllerTest < ActionDispatch::IntegrationTest
     end
 
     context "#destroy" do
-      setup do
-        as_user do
-          @bulk_update_request = create(:bulk_update_request)
-        end
-      end
-
       context "for the creator" do
         should "succeed" do
           delete_auth bulk_update_request_path(@bulk_update_request), @user
@@ -92,12 +75,6 @@ class BulkUpdateRequestsControllerTest < ActionDispatch::IntegrationTest
     end
 
     context "#approve" do
-      setup do
-        as_user do
-          @bulk_update_request = create(:bulk_update_request)
-        end
-      end
-
       context "for a member" do
         should "fail" do
           post_auth approve_bulk_update_request_path(@bulk_update_request), @user