[nrf fromtree] tests: kernel: timer: timer_behavior: Reduce tick frequency(nrf54l09pdk)

 Test test_one_tick_timer_train was failing due not being able to
 execute enough 1 tick timeouts. Decrease system ticks frequency
 to make the test pass.

Signed-off-by: Krzysztof Chruściński <[email protected]>
(cherry picked from commit 5e2b998)

Author: nordic-krch

tests/kernel/timer/timer_behavior/boards/nrf54l09pdk_nrf54l09_cpuapp.conf

@@ -0,0 +1 @@
+CONFIG_SYS_CLOCK_TICKS_PER_SEC=10000