define QT_QML_DEBUG instead of manually instantiating debugging helper

[uclaros]

Apparently you only need to define QT_QML_DEBUG for qml debugging to work.

Fixes #3303

[github-actions]

Pull Request Test Coverage Report for Build 8648253858

Details

• 0 of 0 changed or added relevant lines in 0 files are covered.
• 89 unchanged lines in 2 files lost coverage.
• Overall coverage decreased (-0.01%) to 60.046%

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Files with Coverage Reduction	New Missed Lines	%
input/app/projectsmodel.cpp	1	65.75%
input/app/main.cpp	88	33.23%

Totals
Change from base Build 8628227245:	-0.01%
Covered Lines:	7579
Relevant Lines:	12622

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💛 - Coveralls