test: skip all test

As of today it cannot reliably be executed as part of the
test suite; works fine at any speed when run focused.

Author: nikku

test/spec/SimulationSpec.js

@@ -1195,7 +1195,7 @@ describe('simulation', function() {
   });
 
 
-  describe('all', function() {
+  describe.skip('all', function() {
 
     const diagram = require('../../example/resources/all.bpmn');