Vish Kal, Blood Arbiter loop

The AI keeps activating [[Vish Kal, Blood Arbiter]]'s ability to remove +1/+1 counters even if there are no counters to remove, causing an near-infinite loop. Eventually the AI decides to do something else but then goes back to attempting to remove the counters.

No source file or test is named. Start by reproducing the AI's handling of Vish Kal, Blood Arbiter when no +1/+1 counters are present, then trace the activated-ability decision loop. Done means the AI does not repeatedly attempt the counter-removal ability when there are no counters, with a regression test covering that state.

Written by the indexing model from the issue text.