JIRA: https://jira.spring.io/browse/INT-3899
Previously, within `AbstractPollingEndpoint`, the `Poller` object was
created from `afterPropertiesSet()` as well as `start()` if previously `stopped()`
(`this.initialized == false`).
This precluded modification of the advice chain (e.g. in tests when using
`autoStartup == false`).
Move the poller creation to `start()` so that it is always created then, and does
not require a previous `stop()` to change the advice chain.
2f56bb1329