.rubocop.yml: update to match main configuration

Author: BrewTestBot

.rubocop.yml

@@ -1,14 +1,5 @@
 # This file is synced from `Homebrew/brew` by the `.github` repository, do not modify it directly.
 ---
-plugins:
-- rubocop-md:
-    plugin_class_name: RuboCop::Markdown::Plugin
-- rubocop-performance:
-    plugin_class_name: RuboCop::Performance::Plugin
-- rubocop-rspec:
-    plugin_class_name: RuboCop::RSpec::Plugin
-- rubocop-sorbet:
-    plugin_class_name: RuboCop::Sorbet::Plugin
 AllCops:
   ParserEngine: parser_prism
   TargetRubyVersion: 3.3