tf: standalone apm server aws_os not exist

[carsonip]

regression from #15535

│ Error: Invalid index
│ 
│   on ../infra/terraform/modules/standalone_apm_server/main.tf line 72, in data "aws_ami" "os":
│   72:     values = [local.instance_arch[var.aws_os]]
│     ├────────────────
│     │ local.instance_arch is object with 7 attributes
│     │ var.aws_os is "amzn2-ami-hvm-*-x86_64-ebs"
│ 
│ The given key does not identify an element in this collection value.
╵
╷
│ Error: Invalid index
│ 
│   on ../infra/terraform/modules/standalone_apm_server/main.tf line 85, in data "aws_ami" "os":
│   85:   owners = [local.image_owners[var.aws_os]]
│     ├────────────────
│     │ local.image_owners is object with 7 attributes
│     │ var.aws_os is "amzn2-ami-hvm-*-x86_64-ebs"
│ 
│ The given key does not identify an element in this collection value.
╵

[kruskall]

amzn2

this is no longer a supported OS in >= 9

[carsonip]

@kruskall this is a regression breaking the default benchmark run, including nightly.

[carsonip]

Benchmarking on standalone apm server is still broken on main

╷
│ Error: creating EC2 Instance: InvalidParameterValue: The architecture 'x86_64' of the specified instance type does not match the architecture 'arm64' of the specified AMI. Specify an instance type and an AMI that have matching architectures, and try again. You can use 'describe-instance-types' or 'describe-images' to discover the architecture of the instance type or AMI.
│ 	status code: 400, request id: 68dbc0d4-fa89-46f6-96e7-2a17d2df0179
│ 
│   with module.standalone_apm_server[0].aws_instance.apm,
│   on ../infra/terraform/modules/standalone_apm_server/main.tf line 142, in resource "aws_instance" "apm":
│  142: resource "aws_instance" "apm" {
│ 
╵
make: *** [Makefile:92: apply] Error 1