FIX: Allow group members to freely exit group option incorrectly disabled.

https://meta.discourse.org/t/cannot-check-allow-members-to-leave-group-freely-when-group-is-configured-to-allow-users-to-send-membership-requests-to-group-owners/73400

test/javascripts/acceptance/group-edit-test.js.es6

@@ -43,6 +43,11 @@ QUnit.test("Editing group", assert => {
       'it should disable group public admission input'
     );
 
+    assert.ok(
+      find('.group-edit-public-exit[disabled]').length === 0,
+      'it should not disable group public exit input'
+    );
+
     assert.equal(
       find('.group-edit-membership-request-template').length, 1,
       'it should display the membership request template field'