Simplify translatable tests in admin section

These feature tests were taking too long, we can't run them for every
single model.

I'm taking the approach of using one different model for each test, but
in theory only using a few models covering every possible scenario
would be enough.

spec/features/admin/legislation/draft_versions_spec.rb

@@ -7,12 +7,6 @@ describe "Admin legislation draft versions" do
     login_as(admin.user)
   end
 
-  it_behaves_like "edit_translatable",
-                  "legislation_draft_version",
-                  "edit_admin_legislation_process_draft_version_path",
-                  %w[title changelog],
-                  { "body" => :markdownit }
-
   context "Feature flag" do
 
     scenario "Disabled with a feature flag" do

spec/features/admin/legislation/processes_spec.rb

@@ -7,11 +7,6 @@ describe "Admin collaborative legislation" do
     login_as(admin.user)
   end
 
-  it_behaves_like "edit_translatable",
-                  "legislation_process",
-                  "edit_admin_legislation_process_path",
-                  %w[title summary description additional_info]
-
   it_behaves_like "admin_milestoneable",
                   :legislation_process,
                   "admin_legislation_process_milestones_path"

spec/features/admin/legislation/questions_spec.rb

@@ -9,11 +9,6 @@ describe "Admin legislation questions" do
 
   let!(:process) { create(:legislation_process, title: "An example legislation process") }
 
-  it_behaves_like "edit_translatable",
-                  "legislation_question",
-                  "edit_admin_legislation_process_question_path",
-                  %w[title]
-
   context "Feature flag" do
 
     before do