[APM] Use ML capabilities canAccessML to enable anomaly detection settings #73998
Description
As per the feedback (https://github.com/elastic/kibana/pull/73638/files#r463479399), we should be checking the value of canAccessML instead of only checking for the existance of the ML plugin. This will ensure that the user isn't able to use Anomaly detection settings in cases where they don't have ML enabled in the cluster or otherwise don't have access to ML in kibana.