Reduce length of Bigquery service account

Fix for error:
Error: "account_id" ("appender-wif-trs-pre-production") doesn't match regexp "^[a-z](?:[-a-z0-9]{4,28}[a-z0-9])$"

This change will allow:
- 6 characters for the short service name
- 15 characters for the environment name

aks/dfe_analytics/resources.tf

@@ -1,5 +1,5 @@
 resource "google_service_account" "appender" {
-  account_id   = "appender-wif-${var.service_short}-${var.environment}"
+  account_id   = "app-wif-${var.service_short}-${var.environment}"
   display_name = "Service Account appender to ${var.service_short} in ${var.environment} environment"
   description  = "Configured with workflow identity federation from Azure"
 }