tests: logging: log_benchmark: Prevent flushing logs by ztest

Test is using logging in a different way and flushing logs
after each test case would not work.

Signed-off-by: Krzysztof Chruscinski <[email protected]>

Author: nordic-krch

tests/subsys/logging/log_benchmark/prj.conf

@@ -16,3 +16,4 @@ CONFIG_ASSERT=n
 CONFIG_LOG_STRDUP_POOL_PROFILING=y
 CONFIG_LOG_TEST_CLEAR_MESSAGE_SPACE=n
 CONFIG_APPLICATION_DEFINED_SYSCALL=y
+CONFIG_TEST_LOGGING_FLUSH_AFTER_TEST=n