Change dependency from `github.com/fsouza/go-dockerclient` to `github.com/docker/docker/client`"

What does this MR do?

Switch from github.com/fsouza/go-dockerclient to github.com/docker/docker/client

Why was this MR needed?

We're out of date with go-dockerclient and would rather use the official client, which is now docker/docker/client, not docker/engine-api/client

Are there points in the code the reviewer needs to double check?

Does this MR meet the acceptance criteria?

• CHANGELOG entry added
• Documentation created/updated
• Tests
  • Added for this feature/bug
  • All builds are passing
• Branch has no merge conflicts with master (if you do - rebase it please)

What are the relevant issue numbers?

Closes #1606 (closed)