gitlab-ci: Update Windows builds to MSVC 14.34 toolset
Problems with cmake-gui
when compiled with the MSVC 14.33 toolset,
that did not occur with the MSVC 14.32 toolset, no longer occur with the
MSVC 14.34 toolset. Therefore we can use the new toolset for both normal
CI jobs and the packaging jobs. Revert commit cb8b27a9 from !7597 (merged)
and update the remaining toolset version references.
Fixes: #23859 (closed)
Backport: release
Edited by Brad King