Updates mailrelay to 3.0.5 to decomission the legacy mailrelay server

TF appears to want to do the right thing.

prod/aws-us-gov/mdr-prod-c2/090-instance-mailrelay/terragrunt.hcl

@@ -13,7 +13,7 @@ locals {
 # working directory, into a temporary folder, and execute your Terraform commands in that folder.
 terraform {
   # Double slash is intentional and required to show root of modules
-  source = "git@github.xdr.accenturefederalcyber.com:mdr-engineering/xdr-terraform-modules.git//base/mailrelay?ref=v3.0.0"
+  source = "git@github.xdr.accenturefederalcyber.com:mdr-engineering/xdr-terraform-modules.git//base/mailrelay?ref=v3.0.5"
 }
 
 dependency "vpc-system-services" {
@@ -52,8 +52,6 @@ inputs = {
     Purpose = "Mail Relay - Proxy between our systems and SES"
     Terraform = "aws/${basename(get_parent_terragrunt_dir())}/${path_relative_to_include()}/"
   }
-  # MSOCI-1852 - 2021-09-09 - old_instance_name be removed when old instance is decomissioned
-  old_instance_name = "mailrelay"
   instance_name = "mailrelay2" 
   instance_type = local.account_vars.locals.mailrelay_instance_type
   vpc_id = dependency.vpc-system-services.outputs.vpc_id