A wild and assorted flock of chickens — in every plumage, weight and breed — came home to roost before the Los Angeles County Board of Supervisors last week. All of them were as mad as wet hens, and none of them were pleasant to deal with.But the habitually aloof little kings and queens of the nation’s most populous county had no choice but to deal with each and every one of them, and politely. Most supervisors run for re-election unopposed, answerable only to one another for votes. So the board constitutes perhaps the closest thing California has to a hereditary government, bereft of balances and checks. But this time, the members were finally being held answerable for their unanswerable status.