Don't leak GeneratingEnumeratorCollection in test

Pass the pointers directly to let them be wrapped in job pointers,
instead of deref'ing them to create a shallow reference which will
leak the contents of the elements list.

Fixes:
```
Direct leak of 3648 byte(s) in 114 object(s) allocated from:
    #0 0x7fc23eee2002 in operator new(unsigned long) /usr/src/debug/gcc/gcc/libsanitizer/asan/asan_new_delete.cpp:95
    #1 0x5603a99f0712 in GeneratingEnumeratorCollection::run(QSharedPointer<ThreadWeaver::JobInterface>, ThreadWeaver::Thread*) /home/milian/projects/kde/src/frameworks/threadweaver/autot>

```