test_thread.rb: assert_operator for comparison

* test/ruby/test_thread.rb (test_priority): use assert_operator
  for comparison instead of assert_send.

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@44215 b2dd03c8-39d4-4d8f-98ff-823fe69b080e
test_thread.rb: timing issues

* test/ruby/test_thread.rb: get rid of timing issues and reduce
  sleep times.

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@44216 b2dd03c8-39d4-4d8f-98ff-823fe69b080e