Bump all RDS Modules to v8

[sj-williams]

Background

The changes introduced in our last major release of the RDS module require user action, since the default storage_type variable has changed from gp2 to gp3. This has put us in a place where its proving challenging to get the module version calls lined up across the environments repo.

We have a plan to manage a 'big-bang' no-ops bump across the env repo, by identifying the module call level changes required to push the module bump through without any changes to underlying instances.

Rough outline of steps:

• collate list of all RDS modules currently pinned to 7.2.2, ascertaining their current storage_type value, and also allocated/max_allocated storage fields.

• create script to update modules and insert:

storage_type = "gp2" (or via variables.tf)

allocated_storage = 10 (where not doing so would result in a change like:

  # module.rds-instance.aws_db_instance.rds will be updated in-place
  ~ resource "aws_db_instance" "rds" {
      ~ allocated_storage                     = 10 -> 20

• send brief comms out explaining bump, and reminding users that gp3 is available if they choose to switch over in the future (can point to the release notes for the "how to")