Fix 'remove' method of 'hasMany' relation

Fixes an issue where the 'remove' method of the 'hasMany' relation is not checking for the id of the calling model instance.

The method was removing the first relation with the specified id for the other model, ignoring the id of the model on which it is called, leading to the removal of the wrong relation in the case of 'hasAndBelongsToMany' relations (which uses 'hasMany').