DEV: Add rake plugins:turbo_spec task (#18289)

This leans on our existing `turbo_rspec` implementation to run plugin specs in parallel on all available cores

bin/rake

@@ -2,7 +2,7 @@
 # frozen_string_literal: true
 
 if ENV['RAILS_ENV'] == 'test' && ENV['LOAD_PLUGINS'].nil?
-  if ARGV.include?('db:migrate')
+  if ARGV.include?('db:migrate') || ARGV.include?('parallel:migrate')
     STDERR.puts "You are attempting to run migrations in your test environment and are not loading plugins, setting LOAD_PLUGINS to 1"
     ENV['LOAD_PLUGINS'] = '1'
   end