Switching between gridmaps and other nodes causes selection to be incorrect when returning

[elvisish]

Godot version

3.5.2.rc2

System information

Windows 10

Issue description

When switching between gridmap nodes, if the most recently chosen gridmap has fewer meshes in its MeshLibrary, returning to a previous gridmap node will result in the previously selected mesh being incorrect.

If switching between gridmaps, it will choose the highest possible mesh id in the previously selected gridmap node. If the gridmap meshlibrary ids are the same, it will retain the same chosen id.

If switching between gridmap nodes and, say, a spatial node, it seems to increase the selected meshlibrary id by 36 places. The shown chosen mesh id will be correct, but the actual mesh shown in the editor for placement is 36 places higher.

This fixed the error: #64188 but it seems to still be broken, ideally gridmaps would each store their own previously chosen mesh id and recall it when the gridmap node is selected.

Steps to reproduce

Create two gridmaps and a spatial node.
Add many meshlibrary ids to one of the gridmaps and fewer to the other.
Observe the previously chosen mesh being incorrect unless the two gridmap mesh counts are identical.

Minimal reproduction project

I'd need to make a special project for this as I'm working off my own huge game, but I can do if required.