We should use uplevel:2 in another case.

Like the following scenario with bootsnap, that frames are same or smaller than frame_to_skip(=3).

---
"/Users/hsbt/.local/share/rbenv/versions/3.3-dev/lib/ruby/3.3.0/bundled_gems.rb:69:in `block (2 levels) in replace_require'"
"/Users/hsbt/.local/share/gem/gems/bootsnap-1.18.4/lib/bootsnap/load_path_cache/core_ext/kernel_require.rb:30:in `require'"
"test_warn_bootsnap.rb:11:in `<main>'"
---

lib/bundled_gems.rb

@@ -98,7 +98,7 @@ module Gem::BUNDLED_GEMS
         end
       end
     end
-    1
+    require_found ? 1 : 2
   end
 
   def self.find_gem(path)