Resolve "fix GtEventLoop running indefintely if timeout was set to 0"

[mariusalexander]

Description

Closes #1154

Fixed GtEventLoop not returning if timeout was set to 0.

How Has This Been Tested?

• Checked usages of GtEventLoop
• Added Unittests

Checklist:

• [ ] A test for the new functionality was added (if applicable).
• [ ] All tests run without failure.
• [ ] The changelog has been extended, if this MR contains important changes from the users's point of view.
• [ ] The new code complies with the GTlab's style guide.
• [ ] New interface methods / functions are exported via EXPORT. Non-interface functions are NOT exported.
• [ ] The number of code quality warnings is not increasing.

[mariusalexander]

@rainman110 May you have a look? :)

[mariusalexander]

• What does a timeout of zero even mean?

It should do at least one iteration. The documentation says https://doc.qt.io/qt-6/qtimer.html#interval-prop: (which is exactly what I need/expected)

A QTimer with a timeout interval of 0 will time out as soon as all the events in the window system's event queue have been processed.

Regarding negative values for the timer. I could not find an answer to that in the documentation. But since the eventloop should run idefinetly we do not need a timer for that, therefore I would propose to keep the if-statement as is.