Remove bogus assert

The code was actually completely fine, but the assert was bogus.
detach() can call realloc(d->alloc).

Fixes: QTBUG-73756
Change-Id: I3485bc926dba3f2537e14c0c05d30ff982e6e714
Reviewed-by: Mårten Nordheim <marten.nordheim@qt.io>
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>

src/corelib/tools/qvector.h

@@ -672,7 +672,6 @@ void QVector<T>::realloc(int aalloc, QArrayData::AllocationOptions options)
     Data *x = d;
 
     const bool isShared = d->ref.isShared();
-    Q_ASSERT(aalloc != int(d->alloc) || isShared);
 
     QT_TRY {
         // allocate memory