Add stop_timeout instead of re-using start_timeout

[elgalu]

I think it would be better to add stop_timeout instead of re-using start_timeout here:

kubespawner/kubespawner/spawner.py

Line 1784 in 5040e75

timeout=self.start_timeout,

[minrk]

Makes sense

[consideRatio]

Still relevant issue.

kubespawner/kubespawner/spawner.py

Lines 2011 to 2020 in 44d638b

	try:
	await exponential_backoff(
	lambda: self.pod_reflector.pods.get(self.pod_name, None) is None,
	'pod/%s did not disappear in %s seconds!' % (self.pod_name, self.start_timeout),
	timeout=self.start_timeout,
	)
	except TimeoutError:
	self.log.error("Pod %s did not disappear, restarting pod reflector", self.pod_name)
	self._start_watching_pods(replace=True)
	raise