Rails seeded parallel tests (#2037)

Enable work stealing by default for a tiny speedup at the cost of small
loss in reproducibility.

References https://github.com/rails/rails/pull/56175

Gemfile.lock

@@ -13,7 +13,7 @@ GIT
 
 GIT
   remote: https://github.com/rails/rails.git
-  revision: bf81d40a91880c059ce9d0447219385a2c8e4a15
+  revision: 554970f3e9b520bc302a339c13aa1d98866be3aa
   branch: ast-immediate-variants-process-locally
   specs:
     actioncable (8.2.0.alpha)

Gemfile.saas.lock

@@ -82,7 +82,7 @@ GIT
 
 GIT
   remote: https://github.com/rails/rails.git
-  revision: bf81d40a91880c059ce9d0447219385a2c8e4a15
+  revision: 554970f3e9b520bc302a339c13aa1d98866be3aa
   branch: ast-immediate-variants-process-locally
   specs:
     actioncable (8.2.0.alpha)

test/test_helper.rb

@@ -38,7 +38,7 @@ end
 
 module ActiveSupport
   class TestCase
-    parallelize(workers: :number_of_processors)
+    parallelize workers: :number_of_processors, work_stealing: ENV["WORK_STEALING"] != "false"
 
     # Setup all fixtures in test/fixtures/*.yml for all tests in alphabetical order.
     fixtures :all