Use correct DevOps role in KMS key policies in dev. (#802)

Author: mfjarvis

infra/environments/dev/variables.tfvars

@@ -2,7 +2,7 @@ imms_account_id          = "345594581768"
 dspp_account_id          = "603871901111"
 mns_account_id           = "631615744739"
 admin_role               = "root" # We shouldn't be using the root account. There should be an Admin role
-dev_ops_role             = "role/DevOps"
+dev_ops_role             = "role/aws-reserved/sso.amazonaws.com/eu-west-2/AWSReservedSSO_DEV-IMMS-Devops_745af4f208886ecc"
 dspp_admin_role          = "root"
 mns_admin_role           = "role/nhs-mns-events-lambda-delivery"
 environment              = "dev"