Revert "Detach before setting the d pointer"

Summary:
This reverts commits 04cc49c71bdb948e06ccae2d97d7cc1a1d2f62af as well
as the follow-up partial fix c32c8d002e1216373560c94738841a7a5e1b976b

The whole internal data sync'ing design of the KNewStuff core library
relies on EntryInternal instances explicitely sharing the data.
Changing only EntryInternal to implicitly shared data broke things.
And changed behaviour of that class also for any 3rd-party consumers.

BUG: 386156

Reviewers: whiting, leinir, apol

Reviewed By: leinir

Subscribers: Frameworks

Tags: Frameworks

Differential Revision: https://phabricator.kde.org/D9012