* Two things:
* Change how we populate and clear leader UUID. This fixes a case where
if a standby disconnects from an active node and reconnects, without the
active node restarting, the UUID doesn't change so triggers on a new
active node don't get run.
* Add a bunch of test helpers and minor updates to things.
* Nomad: updating max token length to 256
* Initial support for supporting custom max token name length for Nomad
* simplify/correct tests
* document nomad max_token_name_length
* removed support for max token length env var. Rename field for clarity
* cleanups after removing env var support
* move RandomWithPrefix to testhelpers
* fix spelling
* Remove default 256 value. Use zero as a sentinel value and ignore it
* update docs
