Fix: [AEA-5803] - Update the Notify KID secret to use the new (better labelled) one (#2248)

## Summary

- Routine Change

### Details

Updates the secret for the app KID. Also removes the conditional setting
of parameter values.

`account-resources` PR to add in the new secret (must be merged first):
NHSDigital/electronic-prescription-service-account-resources#1558

After this is merged and deployed to `prod`, this PR will delete the
unused secret:
NHSDigital/electronic-prescription-service-account-resources#1559

---------

Co-authored-by: tstephen-nhs <231503406+tstephen-nhs@users.noreply.github.com>

Author: wildjames

SAMtemplates/functions/main.yaml

@@ -419,7 +419,7 @@ Resources:
           TABLE_NAME: !Ref PrescriptionNotificationStatesTableName
           API_KEY_SECRET: secrets-PSU-Notify-API-Key
           PRIVATE_KEY_SECRET: secrets-PSU-Notify-PrivateKey
-          KID_SECRET: secrets-PSU-Notify-Application-Name
+          KID_SECRET: secrets-PSU-Notify-Application-KID
           NHS_NOTIFY_ROUTING_ID_PARAM: !Ref NotifyRoutingPlanIDParam
           NOTIFY_API_BASE_URL_PARAM: !Ref NotifyAPIBaseURLParam
           MAKE_REAL_NOTIFY_REQUESTS_PARAM: !Ref EnableNotificationsExternalParam