Set outputFileTracingRoot back to projectRoot. In Docker, the parent
(monorepoRoot) was /, which caused Next.js to emit server.js at
.next/standalone/app/server.js and pull in /usr, /root, /proc paths,
breaking from /app.
Fixes#1064
Co-authored-by: Muhammad Ridwan Ramadhan <ridwanramadhan8888@gmail.com>