chore: disable split api routes on middleware until fix is in place

Author: orinokai

demos/middleware/netlify.toml

@@ -3,9 +3,6 @@ command = "npm run build"
 publish = ".next"
 ignore = "if [ $CACHED_COMMIT_REF == $COMMIT_REF ]; then (exit 1); else git diff --quiet $CACHED_COMMIT_REF $COMMIT_REF ../..; fi;"
 
-[build.environment]
-NEXT_SPLIT_API_ROUTES = "true"
-
 [[plugins]]
 package = "@netlify/plugin-nextjs"