On a high load machine, the following test can fail.
This patch simply records the load average with `uptime`.

```
  1) Failure:
TestThreadQueue#test_thr_kill [/tmp/ruby/src/trunk_gcc10/test/ruby/test_thread_queue.rb:239]:
only 165/250 done in 60 seconds.
```

Fixes [Bug #17146]

This test caused issues occasionally on JRuby because it's
possible for a producer thread to run to completion before the
status checks begin. This results in Thread#status returning false
and the =~ call triggering a warning (3.1) or error (3.2) and
either emitting thousands of deprecation warnings or failing
outright.

The patch here introduces a mutex that remains locked until all
producer threads are seen to have started. The lock is then
released and the test proceeds. This prevents any producers from
running to completion, which in turn prevents consumers running to
completion, avoiding the warnings or error calling =~ on false.

This patch also modifies the status checks to to_s the thread
status, preventing any prematurely terminated threads from
triggering similar deprecation warnings or missing method errors
when =~ is called on nil.

This reverts commit bbbec4b87c1e66909f5bee9acd3e460b8c1ad663.
Because the commit is a bug. The `apply_timeout_scale` to scale the timeout is
called 2 times in the process.

The `test/ruby/test_thread_queue.rb#test_thr_kill` is calling
`EnvUtil.apply_timeout_scale`, and
calling `tool/lib/core_assertions.rb#assert_normal_exit`.
calling `tool/lib/envutil.rb#invoke_ruby` (`EnvUtil.invoke_ruby`)
calling the `apply_timeout_scale`.

```
$ make test-all V=1 TESTS="-v test/ruby/test_thread_queue.rb -n TestThreadQueue#test_thr_kill --timeout-scale=2"
```

`assert_normal_exit` uses keyword arguments since 2013, commit
05dd6b194cc29961a7cecfd5c3852f06dd56a871.

`Queue` and `SizedQueue` still check array members.  Only the test of
`ConditionVariable` is useless.

These tests were added at a198bb3929a4562a12b4aa245a297c7d3695149f,
when these classes were `Struct`s.  Since these classes have been
rewritten, these tests no longer make sense.

[Feature #18944]

If both `non_block=true` and `timeout:` are supplied, ArgumentError
is raised.