Bump @tootallnate/once, applicationinsights and @vscode/test-electron (#972)

Removes [@tootallnate/once](https://github.com/TooTallNate/once). It's no longer used after updating ancestor dependencies [@tootallnate/once](https://github.com/TooTallNate/once), [applicationinsights](https://github.com/microsoft/ApplicationInsights-node.js) and [@vscode/test-electron](https://github.com/Microsoft/vscode-test). These dependencies need to be updated together.


Removes `@tootallnate/once`

Updates `applicationinsights` from 2.9.5 to 2.9.8
- [Release notes](https://github.com/microsoft/ApplicationInsights-node.js/releases)
- [Changelog](https://github.com/microsoft/ApplicationInsights-node.js/blob/main/CHANGELOG.md)
- [Commits](https://github.com/microsoft/ApplicationInsights-node.js/commits)

Updates `@vscode/test-electron` from 2.3.9 to 2.5.2
- [Changelog](https://github.com/microsoft/vscode-test/blob/main/CHANGELOG.md)
- [Commits](microsoft/vscode-test@v2.3.9...v2.5.2)

---
updated-dependencies:
- dependency-name: "@tootallnate/once"
  dependency-version: 
  dependency-type: indirect
- dependency-name: applicationinsights
  dependency-version: 2.9.8
  dependency-type: indirect
- dependency-name: "@vscode/test-electron"
  dependency-version: 2.5.2
  dependency-type: direct:development
...

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