Don't set git config features.manyFiles on post install

This reverts #31408, as it also sets the git config value `index.skipHash` which breaks cargo at the moment: rust-lang/cargo#11857

Contributors docs have been updated to recommend a shallow clone in #44158, which should alleviate some of the issues that manyFiles addresses.

package.json

@@ -46,7 +46,7 @@
  "next-no-sourcemaps": "cross-env NEXT_TELEMETRY_DISABLED=1 node --trace-deprecation packages/next/dist/bin/next",
  "clean-trace-jaeger": "rm -rf test/integration/basic/.next && TRACE_TARGET=JAEGER pnpm next build test/integration/basic",
  "debug": "cross-env NEXT_TELEMETRY_DISABLED=1 node --inspect packages/next/dist/bin/next",
- "postinstall": "git config feature.manyFiles true && node scripts/install-native.mjs",
+ "postinstall": "node scripts/install-native.mjs",
  "version": "npx pnpm@7.24.3 install && IS_PUBLISH=yes ./scripts/check-pre-compiled.sh && git add .",
  "prepare": "husky install",
  "sync-react": "node ./scripts/sync-react.js"