Draft: [FIX] ML model use for probability

An attempt to use ML model to get probability result leads to PHP fatal error. This happens because TikiLib::lib('ml')->probaSample() returns an array with the array keys being sample labels but code in use action of ML Service Controller assumed the keys were Tracker item IDs and tries to treat them as such. I modified that part of the code to work with returned array as expected and solving the issue.