These are used to signal the start of the document in a stream of many
documents. As Ansible only supports one YAML document per file this is
unnecessary. About a third of our YAML documents already lacked these.
The tools role is only used on servers which normal staff have SSH
access to since [1].
[1] 7da1e273 ("Cleanup tools")
Fixes: d88c0b95 ("Initialize gluebuddy host")
