[native_sim] k_msleep is incoherent with ztest

[Vidioleola]

Using Zephyr version: v4.1.0-rc3-13-g1b1973799308

When running tests on native_sim/native/64, calling k_sleep, k_msleep or related functions does NOT work as expected.
When running without test framework it works as expected.

Below you can see running a basic test, which should sleep for 10 seconds, took only 5.69 seconds to complete.

INFO    - Total complete:    1/   1  100%  built (not run):    0, filtered:    1, failed:    0, error:    0
INFO    - 2 test scenarios (2 configurations) selected, 1 configurations filtered (1 by static filter, 0 at runtime).
INFO    - 1 of 1 executed test configurations passed (100.00%), 0 built (not run), 0 failed, 0 errored, with no warnings in 5.69 seconds.
INFO    - 1 of 1 executed test cases passed (100.00%) on 1 out of total 948 platforms (0.11%).
INFO    - 1 test configurations executed on platforms, 0 test configurations were only built.

But in the handler logs you can see it thinks 10 seconds elapsed ...

------ TESTSUITE SUMMARY START ------

SUITE PASS - 100.00% [dtls]: pass = 1, fail = 0, skip = 0, total = 1 duration = 10.001 seconds
 - PASS - [dtls.test_secure_coap] duration = 10.001 seconds

------ TESTSUITE SUMMARY END ------

I have reduced the kconfig options to

CONFIG_ZTEST=y
CONFIG_PRINTK=y

and the code to

#include <zephyr/ztest.h>

ZTEST(sleep, test_sleep)
{
    printk("%lld %lld\n", k_uptime_get(), k_uptime_ticks());
    printk("%d\n", k_msleep(10 * 1000));
    printk("%lld %lld\n", k_uptime_get(), k_uptime_ticks());
}

ZTEST_SUITE(sleep, NULL, NULL, NULL, NULL, NULL);

What can cause this? At this point I am trying to look into the systick code.
Thank's!

[Vidioleola]

Managed to found CONFIG_NATIVE_SIM_SLOWDOWN_TO_REAL_TIME...