[nrfconnect] Build all clusters app for nRF7002 with LTO

The flash usage on this app/platform is close to the limit.
Enable LTO to prevent from blocking the incoming PRs.

Signed-off-by: Damian Krolik <damian.krolik@nordicsemi.no>

examples/all-clusters-app/nrfconnect/prj_release.conf

@@ -62,3 +62,7 @@ CONFIG_CHIP_FACTORY_DATA_BUILD=y
 
 # Enable the Read Client for binding purposes
 CONFIG_CHIP_ENABLE_READ_CLIENT=y
+
+# Enable LTO to reduce the flash usage
+CONFIG_LTO=y
+CONFIG_ISR_TABLES_LOCAL_DECLARATION=y