Bugfix LB unregister instance

# Bug

We have two load balancers. LB1 and LB2. We also have instance A that is registered to both LB1 and LB2. When we unregister A from LB1, it is also removed from LB2.

# Cause

There was no filter for load_balancer_id in the remove_targets method.

# Fix

Added said filter