* change registry.delete to return deleted struct
* use pointer to alertRuleInfo instead copying.
* do not access evaluation channel when routine is stopped
* remove stopCh and use context cancellation
* do not return ctx.Err when channel is cancelled because it cancels all other routines
* make alertRuleInfo fields and functions package private
(cherry picked from commit 1a762083d7)
Co-authored-by: Yuriy Tseretyan <tceretian@gmail.com>
5c9c5f2f61