Enables Codebuild for sh-cust; Fixes issue with account standards output

Account standards output annoyingly swaps eveyr time it's applied. Looks
like they fixed it in general, but not in outputs. We don't need all
that it was spitting out, anyhow.

The vars tag just fixes the default apps to build.

To be tagged v4.1.0

base/account_standards_c2/outputs.tf

@@ -1,5 +1,5 @@
 output "account_alerts_sns" {
-  value = aws_sns_topic.account-alerts
+  value = aws_sns_topic.account-alerts.arn
 }
 
 output "cloudtrail_logging_bucket" {

base/codebuild_splunk_apps/vars.tf

@@ -1,10 +1,11 @@
 locals {
   # creates a job for each of these types, using <splunk_prefix>:<server type> as the tag
   splunk_server_types = toset([
+    #"cm",
     #"hf",
     #"idx",
     "sh-es",
-    #"sh-cx",
+    "sh-cust",
   ])
 }