fix: Ignore `tags` for `aws_appautoscaling_target`

[namnd]

Description

Scalable targets created before 2023-03-20 may not have an assigned arn. These resource cannot use tags or participate in default_tags. To prevent terraform plan showing differences that can never be reconciled, use the lifecycle.ignore_changes meta-argument Reference: https://registry.terraform.io/providers/hashicorp/aws/latest/docs/resources/appautoscaling_target

Motivation and Context

See https://github.com/terraform-aws-modules/terraform-aws-rds-aurora/issues/473

Breaking Changes

None

How Has This Been Tested?

• [x] I have tested and validated these changes using one or more of the provided examples/* projects