Description

Closes #12321

With Qt 6.9.0 and later, we no longer need to link with Qt::GuiPrivate.
There was also some unneeded linkage.

Motivation and Context

As documented in #12321, 6.10 change some behaviors around private targets. Avoiding linking as of 6.9.0 is the cleanest path.

How Has This Been Tested?

CI on my fork is green.

Types of changes

• Preemptive Bug fix (non-breaking change which fixes an issue)

• Code cleanup (non-breaking change which makes code smaller or more readable)

Checklist:

• My code has been run through clang-format.
• I have read the contributing document.
• My code is not on the master branch.
• The code has been tested.
• All commit messages are properly formatted and commits squashed where appropriate.
• I have included updates to all appropriate documentation.