* [server] Fix layer order rendering when layers are in groups
Fixes#20810
* Update test images
* [server] Fix order of layers in subgroups
basically: layers in WMS is specified in a comma separated
list where leftmost layer is drawn first (it's at the bottom)
and QGIS layer order is exactly the opposite: first layer
in the TOP (topmost) is drawn last (it is at the top).
For this reason the server reverses the list before passing
it to the renderer.
* Fix order of layers in test
* Update src/server/services/wms/qgswmsrenderer.cpp
1ba6b97f74