samples: counter: alarm: remove platform_allow filterring

Because this is a common testing scenario, almost any counter instance
should be able to run. Some counter instances cannot run this sample
should be filtered by platform_exclude or filter keywords.

Signed-off-by: The Nguyen <the.nguyen.yf@renesas.com>

Author: thenguyenyf

samples/drivers/counter/alarm/sample.yaml

@@ -16,31 +16,6 @@ common:
   depends_on: counter
 tests:
   sample.drivers.counter.alarm:
-    platform_allow:
-      - nucleo_f746zg
-      - nrf51dk/nrf51822
-      - nrf52dk/nrf52832
-      - nrf52840dk/nrf52840
-      - nrf9160dk/nrf9160
-      - samd20_xpro
-      - bl5340_dvk/nrf5340/cpuapp
-      - gd32e103v_eval
-      - gd32e507z_eval
-      - gd32f403z_eval
-      - gd32f450i_eval
-      - gd32f450z_eval
-      - gd32e507v_start
-      - gd32f407v_start
-      - gd32f450v_start
-      - gd32f470i_eval
-      - stm32h735g_disco
-      - stm32h573i_dk
-      - rpi_pico
-      - mr_canhubk3
-      - s32z2xxdc2/s32z270/rtu0
-      - s32z2xxdc2/s32z270/rtu1
-      - s32z2xxdc2@D/s32z270/rtu0
-      - s32z2xxdc2@D/s32z270/rtu1
     integration_platforms:
       - nucleo_f746zg
   sample.drivers.counter.alarm.stm32_rtc: