Do not continue serving variant if it was removed from the split traffic

[ramboz]

At the moment, if you change the split ratio after an experiment ran for a while and assign 0% to one of the variants, you'll still get some traffic from users that have potentially persisted that variant in their local storage.

Expected Behaviour

If we pull a variant from an experiment, it should not get any traffic anymore.

Actual Behaviour

The variant still gets traffic once the choice was persisted to the local storage.