Change alert ids to be deterministic instead of auto generated

[adityaj1107]

Issue by dbbaughe Tuesday Apr 30, 2019 at 20:20 GMT Originally opened as https://github.com/opendistro-for-elasticsearch/alerting/issues/45

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Right now we index alerts and use the auto-generated id's for the documents. We should move to deterministic ids to solve multiple problems.

ACTIVE alerts should use an id of: <monitor_id>-<trigger_id> COMPLETED alerts should use an id of: <monitor_id>-<trigger_id>-<start_time>

Benefits: This would allow us to provide the soon to be created alert's alert_id to the mustache context variable for users to use. Removes the chance of duplicate alerts being created at the same time.

[brijos]

A customer showed interest in setting deterministic ids, but was content with -<monitor_name>

[lezzago]

This can include the execution id as well that happens in chained alerts.

[kennyzhang0819]

I will work on this issue!