test/fiber/test_queue.rb: Make the stuck test fail. (#8791)

	test/fiber/test_queue.rb: Make the stuck tests fail.

	We observed the 2 tests in the `test/fiber/test_queue.rb` getting stuck
	in some GCC compilers in Ubuntu ppc64le focal/jammy, even when the timeout
	`queue.pop(timeout: 0.0001)` is set in the code.

	This commit is to make the tests fail rather than getting stuck.
	---
	 test/fiber/test_queue.rb | 20 ++++++++++++++++----
	 1 file changed, 16 insertions(+), 4 deletions(-)