100K tokens of instructions from diagrams

[alexdima]

I was selfhosting in the vscode repository and using plan mode. I noticed I quickly ran into summarising. On closer inspection, it looks like we include >100K of notebook custom instructions containing diagrams.

panel_editAgent_367acc67.copilotmd

[aeschli]

The main fix is to no longer include images references in instruction files.
Also, I think we should avoid auto-include instructions in the VS Code repo but let the agent pick up relevant instructions.
For that don't use the apply field but use good descriptions. I made that change as well.

[aeschli]

To verify open the vscode repo, in .github/instructions/notebook.instructions.md add applyTo: '**' and run a 'hello' prompt.
Verify in the request log that only notebook.instructions.md got attached but not the svg images