settings: Unhandled error in NVS backend

[lmaciejonczyk]

Describe the bug
I we try to store data which exceeds the available size the NVS settings backend returns success but fails in real.

To Reproduce
Call: settings_save_one( path, p_data, INT_MAX )
Tested on: nrf52840dk_nrf52840 with SETTINGS_NVS enabled

Expected behavior
The function: settings_nvs_save() should return failure code but instead it returns ok.

Impact
Unit tests are not passing: nrfconnect/sdk-nrf#3806

Logs and console output

Environment (please complete the following information):

Additional context
This PR fixes the bug: #31870