feat: Change final_snapshot_identifier when snapshot_identifier changes

[vincentclee]

Description

This change modifies the random_id.snapshot_identifier resource to include var.snapshot_identifier in the keepers block. This ensures that when the snapshot_identifier input changes, a new final_snapshot_identifier is generated accordingly.

Motivation and Context

Previously, changes to the snapshot_identifier input did not trigger regeneration of the final snapshot identifier. This could lead to the DBSnapshotAlreadyExists error during the deletion of a DB instance. Including snapshot_identifier in the keepers ensures the final snapshot is uniquely tied to the correct input, improving consistency and reliability.

Breaking Changes

No, this change is backward compatible with existing configurations. However, users should be aware that any change to the snapshot_identifier input will now result in a new final_snapshot_identifier.

How Has This Been Tested?

• I have updated at least one of the examples/* to demonstrate and validate my change(s)
• I have tested and validated these changes using one or more of the provided examples/* projects

• I have executed pre-commit run -a on my pull request

Run 0

module "database" {
  source = "../../terraform-aws-rds-vincentclee"

  identifier = "vlee"
...
}

Run 1

module "database" {
  source = "../../terraform-aws-rds-vincentclee"

  identifier          = "vlee"
  snapshot_identifier = "final-vlee-ebd61569"
...
}

Run 2

module "database" {
  source = "../../terraform-aws-rds-vincentclee"

  identifier          = "vlee"
  snapshot_identifier = "final-vlee-5f3f46f8"
...
}