Adds portal to account.hcl in PROD

prod/aws-us-gov/mdr-prod-c2/account.hcl

@@ -153,6 +153,7 @@ locals {
     "splunk-indexer" = "i3en.3xlarge",
     "splunk-hf"      = "m5a.xlarge",
     "splunk-sh"      = "m5a.4xlarge",
+    "portal"         = "t3a.medium", # legacy: t2.medium
   }
 
   # Bastion