fix(e2e/tanstackstart-react): remove outdated start-plugin-core pin

The pin to @tanstack/start-plugin-core@1.167.35 was added in #20482 to
work around a broken 1.168.0 release. Since then, @tanstack/react-start
1.167.44+ moved to importing from `@tanstack/start-plugin-core/vite`,
a subpath that only exists in 1.169.0+. The old pin now forces the
broken-against-current-react-start version, so both regular CI and
canary fail with `ERR_PACKAGE_PATH_NOT_EXPORTED: ./vite`.

react-start now declares an exact `start-plugin-core: 1.169.3` dep, so
removing the override lets pnpm resolve the matching version that
actually exports `./vite`.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

Author: nicohrubec

dev-packages/e2e-tests/test-applications/tanstackstart-react/package.json

@@ -45,11 +45,6 @@
   "volta": {
     "extends": "../../package.json"
   },
-  "pnpm": {
-    "overrides": {
-      "@tanstack/start-plugin-core": "1.167.35"
-    }
-  },
   "sentryTest": {
     "variants": [
       {