Adding a separate overlay for nrf54l15 flpr is required because
running tests on console uart fails.
Signed-off-by: Jakub Zymelka <jakub.zymelka@nordicsemi.no>
UART error may be reported with random timing
from either UART in configuration mismatch case.
The test case is now aligned to such behaviour.
Signed-off-by: Bartosz Miller <bartosz.miller@nordicsemi.no>
