AWS EBS, Azure Disk and Azure File operators are now built from cmd/ and pkg/, there is no code used from legacy/ dir and we should remove it.

There are still test manifests in legacy/ directory that are still used! They need to be moved somewhere else + Dockerfile.*.test and CI steps must be updated!

Technically, this is a copy of STOR-1797, but we need a bug to be able to backport aws-ebs changes to 4.15 and not use legacy/ directory there too.