Don't add bundler platforms for JRuby

The gems used by a Rails application on JRuby can't be resolved in
other platforms.

Fixes rails#54894.

Author: rafaelfranca

railties/lib/rails/generators/app_base.rb

@@ -661,7 +661,7 @@ def depends_on_system_test?
       end
 
       def depend_on_bootsnap?
-        !options[:skip_bootsnap] && !options[:dev] && !defined?(JRUBY_VERSION)
+        !options[:skip_bootsnap] && !options[:dev] && !jruby?
       end
 
       def target_rails_prerelease(self_command = "new")
@@ -737,7 +737,7 @@ def run_solid
       end
 
       def add_bundler_platforms
-        if bundle_install?
+        if bundle_install? && !jruby?
           # The vast majority of Rails apps will be deployed on `x86_64-linux`.
           bundle_command("lock --add-platform=x86_64-linux")
 
@@ -746,6 +746,10 @@ def add_bundler_platforms
         end
       end
 
+      def jruby?
+        defined?(JRUBY_VERSION)
+      end
+
       def empty_directory_with_keep_file(destination, config = {})
         empty_directory(destination, config)
         keep_file(destination)