Revert "Add debug info for flaky test_warmup_frees_pages"

This reverts commit db3b814.

This debugging information is no longer needed.

Author: peterzhu2118

test/ruby/test_process.rb

@@ -2776,7 +2776,7 @@ def test_warmup_frees_pages
 
       # Number of pages freed should cause equal increase in number of allocatable pages.
       assert_equal(total_pages_before, GC.stat(:heap_eden_pages) + GC.stat(:heap_allocatable_pages))
-      assert_equal(0, GC.stat(:heap_tomb_pages), GC.stat)
+      assert_equal(0, GC.stat(:heap_tomb_pages))
       assert_operator(GC.stat(:total_freed_pages), :>, 0)
     end;
   end