Smoke test flake: Data Loss (insiders -> insiders) - verifies opened editors are restored

[Tyriar]

https://dev.azure.com/monacotools/Monaco/_build/results?buildId=178251&view=results

  1) VSCode Smoke Tests (Electron)
       Data Loss (insiders -> insiders)
         verifies opened editors are restored:
     Error: Smoke test exit call did not terminate process after 20s, giving up
      at /__w/1/s/test/automation/src/code.ts:169:14

[bpasero]

The log indicates that after 20 seconds after we have called exit, the VSCode process is still lurking around. The flow goes like this;

• send a message to VSCode to quit
• wait for 10 seconds until calling treekill
• treekill fails here actually
• after 20 seconds give up and report an error

We did this to make sure no previous running version of VSCode interferes with the next run of a smoke test to avoid misleading error failures.

I don't currently have a good idea how to diagnose why the VSCode process would not terminate when being asked to...

[bpasero]

I am no longer failing when treekill fails, via #155577