This applies the same fix to `digitalocean_ssh_key` as #5588 applies to
droplets. Fixes#5402. The report there gives weight to my theory that
this occurs when there are transport issues.
The error string for 404s on DNS domains has (apparently)
changed, causing things to be a little sad when you modify
DNS domains from the DO console instead of terraform. This
is just the same fix as was applied to droplets around this
time last month.
While I was at it I just fixed this everywhere I saw it in the
DO provider source tree.
James Nugent