WebEngine 6.10 snapshots do not ship with debug resources

Following https://codereview.qt-project.org/c/qt/qtwebengine/+/624746 , WebEngine debug+release builds are expected to emit two versions of their resource files. The current 6.10 snapshots, as downloaded through the maintenance tool, do not reflect that; the only resources shipped are release mode ones. As a result, the effects of QTBUG-131897 can still be observed in debug mode. Also, since windeployqt now expects the debug files to be present, debug mode deployment will also fail.