samples: boards: st: power_mgmt remove standby_shutdown sample

Remove samples/boards/st/power_mgmt/standby_shutdown.

Sample standby_shutdown in boards/st/power_mgmt includes 2 examples.
One demonstrates wakeup from shutdown using a wakeup pin which is already
implemented in samples/boards/st/power_mgmt/wkup_pins. The other
demonstrates wakeup from SoC STANDBY mode using a wakeup pin. However
it enters SoC STANDBY mode through pm_state_force() whereas
STANDBY mode is not a PM standby or idle state, it is rather a shutdown
with possibly only a unique small SRAM retention, not allowing retention
of the system as expected from Zephyr standby or idle state flavors.
Therefore this second scenario is not applicable and can be removed.

Update doc redirection to link removed sample documentation to ST board
power management related samples documentation.

Signed-off-by: Etienne Carriere <[email protected]>

Author: etienne-lms

doc/_scripts/redirects.py

@@ -272,6 +272,7 @@
     ('samples/boards/nrf/system_off/README', 'samples/boards/nordic/system_off/README'),
     ('samples/boards/nxp_s32/netc/README', 'samples/boards/nxp/s32/netc/README'),
     ('samples/boards/qomu/README', 'samples/boards/quicklogic/qomu/README'),
+    ('samples/boards/st/power_mgmt/standby_shutdown/README', 'samples/boards/st/power_mgmt/index'),
     ('samples/boards/stm32/backup_sram/README', 'samples/boards/st/backup_sram/README'),
     ('samples/boards/stm32/bluetooth/interactive_gui/README', 'samples/boards/st/bluetooth/interactive_gui/README'),
     ('samples/boards/stm32/ccm/README', 'samples/boards/st/ccm/README'),