[INTERNAL][FIX] allow usage of testrunner with older UI5 versions

- added fall back to previous jQuery versions
- added check for blanket in case it couldn't be loaded

Change-Id: Ibbcb957b7a7fce4ae319cee0a4c71ca79164be61
Merge "[INTERNAL][FIX] allow usage of testrunner with older UI5 versions"