[Infrastructure UI][Rules] Specify recovery context for Log Threshold rule type

[simianhacker]

The alerting framework has recently merged a PR to provide rule executors with the ability to specify context for recovered alerts. Details are available in the PR and in the alerting README but essentially,

1. Rule types should set doesSetRecoveryContext to true on the rule type. This allows context variables to appear in the action variable list in the UI for the recovered action group.
2. Inside the rule executor, when the executor has finished scheduling actions for active alerts, the following code should be added:

// Call done() to gain access to recovery utils
// If `doesSetRecoveryContext` is set to `false`, getRecoveredAlerts() returns an empty list
const { getRecoveredAlerts } = alertsFactory.done();

for (const alert of getRecoveredAlerts()) {
	const alertId = alert.getId();
	alert.setContext({
		CONTEXT HERE!
	})
}

Note that currently, we expect the recovered context to match the existing typing for context variables on the rule.

Related to: #126279

[elasticmachine]

Pinging @elastic/infra-monitoring-ui (Team:Infra Monitoring UI)

[Kerry350]

Apologies I hadn't seen you'd added issues for this as they weren't linked on the Meta issue. I'm going to link what you've added there. And I'm going to close this one in favour of #127123 purely because it's got implementation hints for that rule type.