Refactor install-test-workspace

[g-chao]

Summary

Before, the install-test-worspace is a standalone pnpm workspace project inside Rushstack. Now, we have integrated the pnpm-sync feature, so we can refactor this project to use pnpm-sync to manage injected dependencies.

Details

1. Enable usePnpmSyncForInjectedDependencies in experiments.json
2. Refactor install-test-worspace folder structure

How it was tested

Make sure all CI checks passed in the new set up

Impacted documentation

N/A

[iclanton]

The new projects should have build cache configured.