Invalidate uv.lock if registry sources are removed (#6026)

## Summary

Now, if you resolve against a registry, then swap it out for another, we
won't reuse the lockfile. (If you don't provide any registry
configuration, then we won't enforce this, so that `uv lock --index-url
foo` and `uv lock` is stable.)

Closes https://github.com/astral-sh/uv/issues/5920.

scripts/scenarios/templates/lock.mustache

@@ -76,7 +76,7 @@ fn {{module_name}}() -> Result<()> {
         .lock()
         .env_remove("UV_EXCLUDE_NEWER")
         .arg("--index-url")
-        .arg("https://astral-sh.github.io/packse/0.3.31/simple-html/")
+        .arg(packse_index_url())
         .assert()
         .success();
     let lock2 = fs_err::read_to_string(context.temp_dir.join("uv.lock"))?;