Re-add spec for `job_token_scope_enabled` default

This spec was removed previously because it failed on CI when we were
updating the `job_token_scope_enabled` field default from false to true.
It can now be safely re-added with the new default.

spec/models/project_ci_cd_setting_spec.rb

@@ -21,6 +21,12 @@ RSpec.describe ProjectCiCdSetting do
     end
   end
 
+  describe '#job_token_scope_enabled' do
+    it 'is true by default' do
+      expect(described_class.new.job_token_scope_enabled).to be_truthy
+    end
+  end
+
   describe '#default_git_depth' do
     let(:default_value) { described_class::DEFAULT_GIT_DEPTH }