fix(examples): use 'n' instead of '0'/'false' for bool Kconfig defaults

'0' and 'false' are not valid values for a bool symbol. The parser emits
a note and falls back to 'n', so the resulting configuration is correct
but the build is noisy. Set the two remaining example symbols to
'default n' to make the value explicit and silence the note.

examples/peripherals/twai/twai_utils/main/Kconfig.projbuild

@@ -6,7 +6,7 @@ menu "TWAI Configuration"
     config EXAMPLE_ENABLE_TWAI_FD
         bool "Enable TWAI-FD Support"
         depends on SOC_TWAI_FD_SUPPORTED
-        default false
+        default n
         help
             Enable TWAI-FD (Flexible Data-rate) support.
             Allows up to 64 bytes of data per frame and dual bit rates.

examples/wifi/scan/main/Kconfig.projbuild

@@ -9,7 +9,7 @@ menu "Example Configuration"
 
     config EXAMPLE_USE_SCAN_CHANNEL_BITMAP
         bool "Scan only non overlapping channels using Channel bitmap"
-        default 0
+        default n
         help
             Enable this to scan only the non overlapping channels i.e 1,6,11 by mentioning a channel bitmap
             in scan config. If you wish to scan a different set of specific channels, please edit the channel_list