This is a Bug Report

Description

I am trying to configure a metric filter alarm with a given filter pattern for the function under my service,

custom:
  alerts:
    topics:
      alarm: 
        topic: arn:aws:sns:eu-west-1:704255512929:CloudWatch-ErrorLogs
    function:
      - name: AnAlarm
        metric: AnError
        treatMissingData: notBreaching
        threshold: 0
        statistic: Sum
        period: 60
        evaluationPeriods: 1
        comparisonOperator: GreaterThanThreshold
        pattern: '[ERROR]'

I was expecting this to create a single metric filter (ERROR) linked a single alarm that is then linked to an SNS Topic (CloudWatch-ErrorLogs), however what is actually happening is 2 metric filters are being created, one with a suffix ALERT and another with a suffix OK. Both of these are then linked to the same metric and the same alert.

From reviewing the code it appears there is code specific to create 2 metric filters, one for the Alert and one for the OK and I wondered why this was the case? Would it be possible to support a way of configuring it to exclude the OK metric filters?

Additional Data

• Serverless Framework Version: 1.26.0: