This allows customizing alert thresholds for http elb and target 5xx
errors. This will prevent a single 5xx from triggering an alert if we
decide the thresholds should be higher. The default 120 seconds with 0
tolerance will be used if nothing is passed in, but alternatives can be
specified by a threshold and an interval.
closes#18776
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Co-authored-by: Luke Heath <luke@fleetdm.com>
