tests: posix: cond: test to ensure there is no resource leakage
tests: posix: cond: test to ensure there is no resource leakage

Add a test to ensure that `pthread_cond_t` can be used over
and over again and that there is no resource leakage with proper
usage.

Signed-off-by: Chris Friedt <b335fc22cf1358c7e834a5788f93b9f24396b889@meta.com>

zephyrproject-rtos/zephyr,zephyrproject-rtos/zephyr,zephyrproject-rtos/zephyr,zephyrproject-rtos/zephyr,zephyrproject-rtos/zephyr