Use _qt_internal_find_third_party_dependencies instead.
We rely on the inner find_dependency call to set the
Qt6_NOT_FOUND_MESSAGE message when a dependency is not found.
This implies removing the custom FATAL_ERROR handling
and relying on the parent find_package to display the
Qt6_NOT_FOUND_MESSAGE message.
We also clear Qt6_FIND_COMPONENTS if a dependency is not found.
No need to look for Qt packages if the Qt6 dependency was not met.
This reduces the amount of recursive error messages.
Pick-to: 6.4
Task-number: QTBUG-104998
Change-Id: I5c611aaededfa63eb507ec5385b37a2fb6fcc698
Reviewed-by: Jörg Bornemann <joerg.bornemann@qt.io>
6a2358e20f