Several APIs in Qt are deprecated, and we don't want application code to use those APIs anymore. However, Qt code itself often still uses those APIs, both in library code, in examples, and in tests.
We need to remove all usage of deprecated API from the code. We still need to test the deprecated APIs as long as they are not removed completely, but that test code would ideally live in a separate test case.
The acceptance criteria is that Qt builds with those deprecated APIs disabled.