fix dynamic setting of max detector/feature limit

[ylwu-amzn]

Issue #, if available:

Description of changes:

• fix dynamic setting of max detector/feature limit

PUT _cluster/settings
{
    "transient" : {
        "opendistro.anomaly_detection.max_anomaly_detectors" : 1
    }
}

Create the second detector and will get error:

{
    "error": {
        "root_cause": [
            {
                "type": "illegal_argument_exception",
                "reason": "Can't create anomaly detector more than 1"
            }
        ],
        "type": "illegal_argument_exception",
        "reason": "Can't create anomaly detector more than 1"
    },
    "status": 400
}

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[yizheliu-amazon]

LGTM. Just curious: it looks like such limit settings in ActionHandler doesn't work, while it works in Action, can you help me understand what's the reason behind it?

[ylwu-amzn]

LGTM. Just curious: it looks like such limit settings in ActionHandler doesn't work, while it works in Action, can you help me understand what's the reason behind it?

Action is singleton while ActionHandler is not. We create a new ActionHandler for each request.