Do not leak CollectionExecuteWrapper of dequeued collections

When the collection gets dequeued the execute wrapper never got
cleanup called, thus it would get leaked. This patch fixes it:
```
Direct leak of 24 byte(s) in 1 object(s) allocated from:
    #0 0x7fc7c54e2002 in operator new(unsigned long) /usr/src/debug/gcc/gcc/libsanitizer/asan/asan_new_delete.cpp:95
    #1 0x7fc7c4ec67a2 in ThreadWeaver::Collection::aboutToBeQueued_locked(ThreadWeaver::QueueAPI*) /home/milian/projects/kde/src/frameworks/threadweaver/src/collection.cpp:77
    #2 0x7fc7c4f13245 in ThreadWeaver::Job::aboutToBeQueued(ThreadWeaver::QueueAPI*) /home/milian/projects/kde/src/frameworks/threadweaver/src/job.cpp:138
    #3 0x7fc7c4f6b8bb in ThreadWeaver::Weaver::enqueue_p(QList<QSharedPointer<ThreadWeaver::JobInterface> > const&) /home/milian/projects/kde/src/frameworks/threadweaver/src/weaver.cpp:221
    #4 0x7fc7c4f974e3 in ThreadWeaver::WeaverImplState::enqueue(QList<QSharedPointer<ThreadWeaver::JobInterface> > const&) /home/milian/projects/kde/src/frameworks/threadweaver/src/weaverimplstate.cpp:59
    #5 0x7fc7c4f6ad52 in ThreadWeaver::Weaver::enqueue(QList<QSharedPointer<ThreadWeaver::JobInterface> > const&) /home/milian/projects/kde/src/frameworks/threadweaver/src/weaver.cpp:207
    #6 0x7fc7c4f4048b in ThreadWeaver::Queue::enqueue(QList<QSharedPointer<ThreadWeaver::JobInterface> > const&) /home/milian/projects/kde/src/frameworks/threadweaver/src/queue.cpp:169
    #7 0x7fc7c4f4084e in ThreadWeaver::Queue::enqueue(QSharedPointer<ThreadWeaver::JobInterface> const&) /home/milian/projects/kde/src/frameworks/threadweaver/src/queue.cpp:174
    #8 0x55888b3c19a9 in QSharedPointer<ThreadWeaver::JobInterface> ThreadWeaver::enqueue<QSharedPointer<ThreadWeaver::JobInterface> >(ThreadWeaver::Queue*, QSharedPointer<ThreadWeaver::JobInterface>) /home/milian/projects/kde/src/frameworks/threadweaver/src/queueing.h:68
    #9 0x55888b3c1b09 in ThreadWeaver::enqueue_raw(ThreadWeaver::Queue*, ThreadWeaver::JobInterface*) /home/milian/projects/kde/src/frameworks/threadweaver/src/queueing.h:82
    #10 0x55888b39b805 in JobTests::DequeueSuspendedSequenceTest() /home/milian/projects/kde/src/frameworks/threadweaver/autotests/JobTests.cpp:900
    #11 0x55888b3aee9e in JobTests::qt_static_metacall(QObject*, QMetaObject::Call, int, void**) /home/milian/projects/kde/build/frameworks/threadweaver/autotests/ThreadWeaverJobTests_autogen/include/moc_JobTests.cpp:551
    #12 0x7fc7c47500a4 in QMetaMethodInvoker::invokeImpl(QMetaMethod, void*, Qt::ConnectionType, long long, void const* const*, char const* const*, QtPrivate::QMetaTypeInterface const* const*) (/usr/lib/libQt6Core.so.6+0x1500a4) (BuildId: b6b6413f12bdfa0f594dbec300f816d4442d5baf)
    #13 0x7fc7c475040b in QMetaMethod::invokeImpl(QMetaMethod, void*, Qt::ConnectionType, long long, void const* const*, char const* const*, QtPrivate::QMetaTypeInterface const* const*) (/usr/lib/libQt6Core.so.6+0x15040b) (BuildId: b6b6413f12bdfa0f594dbec300f816d4442d5baf)
```