Remove broken and obsolete VisualScript nodes

[Gallilus]

Describe the project you are working on

General VisualScript improvements and learning c++

Describe the problem or limitation you are having in your project

Considering it's better to have fewer but working vs_nodes I would like to delete a few broken and obsolete nodes.

1. As described in PR 54663 VisualScriptVariable... is obsolete.
2. As described in PR 48783 VisualScriptSubCall is not working.
3. VisualScriptYieldSignal is not working VisualScriptYield needs to be renamed to await to match GDScript. Proposal 3036

Describe the feature / enhancement and how it helps to overcome the problem or limitation

Delete stuff

Describe how your proposal will work, with code, pseudo-code, mock-ups, and/or diagrams

Delete stuff

If this enhancement will not be used often, can it be worked around with a few lines of script?

These vs_nodes are not being used often.

Is there a reason why this should be core and not an add-on in the asset library?

Delete stuff