taskrunner: Use a random suffix for Task Config
taskrunner: Use a random suffix for Task Config

The RestartCount is not really suitable for use as a source of
uniqueness within task invocations as it is not monotonic, and interacts
with the restart stanza in a users config, so conflates restarts due to
task failures, with restarts due to enviromental changes, such as consul
template or vault secrets changing.

Here we instead use a substring from a uuid, which is more random than
we strictly need, but is nicer than rolling our own random string
generator here.

burdandrei/nomad,hashicorp/nomad,burdandrei/nomad,hashicorp/nomad,hashicorp/nomad,dvusboy/nomad,hashicorp/nomad,hashicorp/nomad,dvusboy/nomad,burdandrei/nomad,burdandrei/nomad,dvusboy/nomad,dvusboy/nomad,burdandrei/nomad,dvusboy/nomad,burdandrei/nomad,hashicorp/nomad,burdandrei/nomad,dvusboy/nomad,dvusboy/nomad