Add rule cancellation support for metrics threshold and log threshold rule types

[pmuellr]

The alerting system now supports cancellation, which is currently only driven via timeouts. A rule can check manually if it's been cancelled, while it's running, and can get "free" cancellation support via an instrumented ES client. The PR [Alerting] Using abortable es client in stack rules #122435 is doing this work for the stack alerts, and should be a good example to follow when adding cancellation support to a rule executor.

While we want ALL rules to be able to support cancellation in this way, I've created this specific issue for metrics threshold and log threshold rule types, as they've been the rule types that we've seen most frequently go over the rule timeout (5 minutes).

[simianhacker]

The framework already supports an abortable client

https://github.com/elastic/kibana/blob/main/x-pack/plugins/alerting/server/lib/wrap_scoped_cluster_client.ts#L140-L145