Revert "Using --build-backend in uv init implies --package (#8837)" (#8850)

This reverts commit 515993c743 from
https://github.com/astral-sh/uv/pull/8837 as it was already implemented
differently in https://github.com/astral-sh/uv/pull/8593 and I missed it

crates/uv/src/commands/project/init.rs

@@ -643,7 +643,7 @@ impl InitProjectKind {
         let mut pyproject = pyproject_project(name, requires_python, author.as_ref(), no_readme);
 
         // Include additional project configuration for packaged applications
-        if package || build_backend.is_some() {
+        if package {
             // Since it'll be packaged, we can add a `[project.scripts]` entry
             pyproject.push('\n');
             pyproject.push_str(&pyproject_project_scripts(name, name.as_str(), "main"));