fix: use current partition instead of assuming aws (#1274)

## Description

Don't hardcode the aws partition as it is not always `aws`, e.g. gov
cloud, China.

Fixes #1273 

## Verification

I cherry picked this against the 9.2.0 tag and verified that it applies
against a gov-cloud account.

---------

Co-authored-by: Matthias Kay <matthias.kay@hlag.com>

Author: joelryan2k

modules/terminate-agent-hook/iam.tf

@@ -189,5 +189,5 @@ resource "aws_iam_role_policy_attachment" "spot_request_housekeeping" {
 
 resource "aws_iam_role_policy_attachment" "aws_lambda_vpc_access_execution_role" {
   role       = aws_iam_role.lambda.name
-  policy_arn = "arn:aws:iam::aws:policy/service-role/AWSLambdaVPCAccessExecutionRole"
+  policy_arn = "arn:${data.aws_partition.current.partition}:iam::aws:policy/service-role/AWSLambdaVPCAccessExecutionRole"
 }

policies/kms-policy.json

@@ -34,7 +34,7 @@
       "Effect": "Allow",
       "Principal": {
         "AWS": [
-          "arn:aws:iam::${account_id}:role/aws-service-role/autoscaling.amazonaws.com/AWSServiceRoleForAutoScaling"
+          "arn:${partition}:iam::${account_id}:role/aws-service-role/autoscaling.amazonaws.com/AWSServiceRoleForAutoScaling"
         ]
       },
       "Action": [