[Optimization] Copy the EFS's Backup Policy to our Backups Vault

### Is your feature request related to a problem? Please describe.

I noticed our vault doesn't have a policy by default, and their managed vault does. It'd be easy to copy it over, and it'd stop anything from accidentally deleting the resources.

Main catch is if I want to create a custom resource that removes it's snapshots on delete (if the bucket is ALSO set to be removed), this would block that from triggering (The `"backup:DeleteRecoveryPoint"`).

```json
{
"Version": "2012-10-17",
"Statement": [
{
"Effect": "Deny",
"Principal": {
"AWS": "*"
},
"Action": [
"backup:DeleteBackupVault",
"backup:DeleteBackupVaultAccessPolicy",
"backup:DeleteRecoveryPoint",
"backup:StartCopyJob",
"backup:StartRestoreJob",
"backup:UpdateRecoveryPointLifecycle"
],
"Resource": "*"
}
]
}
```

### Describe the solution you'd like

_No response_

### Describe alternatives you've considered

_No response_

### Acknowledgements

- [ ] I may be able to implement this feature request
- [ ] This feature might incur a breaking change

No file, test, or entry point is named. Locate the AWS Backup vault definition and compare its access policy with the managed EFS vault policy shown in the issue; done means the intended deny actions are applied while the recovery-point deletion concern is addressed or documented.

Written by the indexing model from the issue text.