When `ui_` include directives have different paths than `CMakeLists.txt`,
the dependency graph is not generated correctly. This is the root cause
of #16776. However, when #26135 was fixed by commit 5363bebc1e (Autogen:
Fix compilation of unchanged source files, 2024-07-16, v3.31.0-rc1~328^2),
it made #16776 worse: the build is always dirty. Revert the fix for now.
Fixes: #26485
Issue: #26135
Issue: #25436
In commit 5363bebc1e (Autogen: Fix compilation of unchanged source files,
2024-07-16, v3.31.0-rc1~328^2) we relied on Ninja Multi-Config dependency graph
optimizations from commit 7c39dabdbc (Autogen: AUTO*_EXECUTABLE: add support
for per-config values, 2023-10-18, v3.29.0-rc1~105^2~1). However, those graph
optimizations are conditional on versions of Qt that enable
[`AUTOGEN_BETTER_GRAPH_MULTI_CONFIG`](https://codereview.qt-project.org/c/qt/qtbase/+/513648).
`UseBetterGraph` should be checked to add ui files to `timestampByproducts`.
Fixes: #26475
Since generated `ui` headers are added as byproducts of the autogen
target, it causes to compilation of unchanged files.
This commits adds generated `ui` headers to byproducts of the
timestamp target instead of the autogen target's.
Fixes: #25436Fixes: #26135
