bundler: Fix rubygems test_dir.

Co-Authored-By: Claude <noreply@anthropic.com>

Author: junaruga

spec/bundler/fetcher/gem_remote_fetcher_local_ssl_server_spec.rb

@@ -1,7 +1,7 @@
 # frozen_string_literal: true
 
-require_relative "../../../test/rubygems/local_ssl_server_utilities"
 require "bundler/fetcher"
+require Spec::Path.rubygems_test_dir.join("local_ssl_server_utilities")
 
 RSpec.describe "Bundler::Fetcher local SSL server", if: Gem::HAVE_OPENSSL do
   include Gem::LocalSSLServerUtilities

spec/support/path.rb

@@ -79,6 +79,10 @@ def spec_dir
       @spec_dir ||= source_root.join(ruby_core? ? "spec/bundler" : "../spec")
     end
 
+    def rubygems_test_dir
+      @rubygems_test_dir ||= source_root.join(ruby_core? ? "test/rubygems" : "../test/rubygems")
+    end
+
     def man_dir
       @man_dir ||= lib_dir.join("bundler/man")
     end