* Fix leaked Vault LifetimeRenewers
When the Vault CA Provider is reconfigured we do not stop the
LifetimeRenewers which can cause them to leak until the Consul processes
recycles. On Configure execute stopWatcher if it exists and is not nil
before starting a new renewal
* Add jitter before restarting the LifetimeWatcher
If we fail to login to Vault or our token is no longer valid we can
overwhelm a Vault instance with many requests very quickly by restarting
the LifetimeWatcher. Before restarting the LifetimeWatcher provide a
backoff time of 1 second or less.
* Use a retry.Waiter instead of RandomStagger
* changelog
* gofmt'd
* Swap out bool for atomic.Unit32 in test
* Provide some extra clarification in comment and changelog
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