Consistent key separation between mgmt and target accounts

[ZIJ]

Surfaced in the discussion with @SalvoRusso8

Comment by @Spartakovic:

It’s a bit all over the place currently unfortunately

• Aws: You can configure lock with either DIGGER_ prefixed keys, or normal aws access keys. Terraform will be using normal aws keys
• Azure: You have to configure lock with DIGGER_ prefixed azure creds. Terraform will be using normal setup
• GCP: Both locks and the terraform will be using the same keys