test: threads: replace test_thread_noreturn

test: threads: replace test_thread_noreturn

While POSIX threads are cancellable and may be asynchronously cancelled,
their cancellation is not guaranteed by the POSIX standard.

test_thread_noreturn, which simulates a long-running possibly
unresponsive thread:

	THREAD #1		THREAD #2
	LOCK L1
	SPAWN #2
				LOCK L1

On MacOS, cancelling such thread only queues cancellation request, but
the following pthread_join hangs.

Replace this implementation by an unbounded sequence of sleeps instead.

Signed-off-by: Čestmír Kalina <ckalina@redhat.com>
Reviewed-by: Hugo Landau <hlandau@openssl.org>
Reviewed-by: Tomas Mraz <tomas@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/19433)