tests: subsys: debug: cpu_load: debug.cpu_load.periodic_report reports timeout

[katgiadla]

Describe the bug
The test tests/subsys/debug/cpu_load/debug.cpu_load.periodic_report

Observed for

• nrf5340dk/nrf5340/cpuapp/ns
• nrf9160dk@0.14.0/nrf9160/ns
• nrf9160dk@0.14.0/nrf9160

To Reproduce
Steps to reproduce the behavior:

1. have nrf9160dk@0.14.0/nrf9160 connected
2. go to your zephyr dir
3. call ./scripts/twister -T tests/subsys/debug/cpu_load -p nrf9160dk@0.14.0/nrf9160 --device-testing --device-serial /dev/ttyACM0 -v --inline-logs --west-flash="--erase"
4. See console output with error

Expected behavior
Valid console output

Impact
Not clear

Logs and console output

*** Booting Zephyr OS build v4.1.0-567-g25f3de75a29a ***
Running TESTSUITE cpu_load
===================================================================
START - test_load
 PASS - test_load in 0.300 seconds
===================================================================
START - test_periodic_report
*** Booting Zephyr OS build v4.1.0-567-g25f3de75a29a ***
Running TESTSUITE cpu_load
===================================================================
START - test_load
 PASS - test_load in 0.300 seconds
===================================================================
START - test_periodic_report
*** Booting Zephyr OS build v4.1.0-567-g25f3de75a29a ***
...

Environment (please complete the following information):

• OS: Ubuntu 20.04.1 LTS
• Toolchain Zephyr SDK 0.17.0
• Commit SHA or Version used: v4.1.0-567-g25f3de

Additional information:
Probably introducedy by commit 688b561