Revert "Revert "Re-enable test_ractor for YJIT""

This reverts commit 9792d9e40f.

Ractor implementation has been rewritten. Let's see if it works now.

bootstraptest/test_ractor.rb

@@ -479,7 +479,6 @@ assert_equal 'ok', %q{
 }
 
 # multiple Ractors can receive (wait) from one Ractor
-yjit_enabled = ENV.key?('RUBY_YJIT_ENABLE') || ENV.fetch('RUN_OPTS', '').include?('yjit')
 assert_equal '[0, 1, 2, 3, 4, 5, 6, 7, 8, 9]', %q{
   pipe = Ractor.new do
     loop do
@@ -502,8 +501,7 @@ assert_equal '[0, 1, 2, 3, 4, 5, 6, 7, 8, 9]', %q{
     rs.delete r
     n
   }.sort
-} unless /mswin/ =~ RUBY_PLATFORM || # randomly hangs on mswin https://github.com/ruby/ruby/actions/runs/3753871445/jobs/6377551069#step:20:131
-  yjit_enabled # flaky with YJIT https://github.com/ruby/ruby/actions/runs/3603398545/jobs/6071549328#step:18:33
+} unless /mswin/ =~ RUBY_PLATFORM # randomly hangs on mswin https://github.com/ruby/ruby/actions/runs/3753871445/jobs/6377551069#step:20:131
 
 # Ractor.select also support multiple take, receive and yield
 assert_equal '[true, true, true]', %q{
@@ -1493,7 +1491,7 @@ assert_equal "#{n}#{n}", %Q{
       end
     end
   }.map{|r| r.take}.join
-} unless yjit_enabled # flaky with YJIT https://github.com/ruby/ruby/actions/runs/3692339025/jobs/6251137785
+}
 
 # NameError
 assert_equal "ok", %q{
@@ -1534,7 +1532,7 @@ assert_equal "ok", %q{
 
   1_000.times { idle_worker, tmp_reporter = Ractor.select(*workers) }
   "ok"
-} unless yjit_enabled # flaky with YJIT https://github.com/ruby/ruby/actions/runs/3575374374/jobs/6011846425
+}
 
 assert_equal "ok", %q{
   def foo(*); ->{ super }; end