One bus: the AMQP transport is gone from the controller

The mesh runs on the seat's bus alone (novox/hq ADR 0131, design 28 task 5.5). The old
transport's consume loop, build request, tool ask, management API and account scoping are
deleted, and the bus switch with them; the controller connects to the broker seat and to
nothing else. The store-window tests keep their assertions on a bus-less fake, and the tests
that only made sense for the old transport's in-memory holding go with it.

internal/broker/onnats_test.go

@@ -1,43 +1,11 @@
 package broker
 
 import (
-	"strings"
 	"testing"
 )
 
 // Which bus the mesh is on is one fact, and being told about both is refused.
 //
-// **Not a warning.** A mesh half on each bus is one where a declaration goes out on one and the
-// report comes back on the other, and every component reports success while it happens — which is
-// the exact failure ADR 0074 exists to catch, arriving through configuration instead of through code.
-func TestBeingToldAboutBothBusesIsRefused(t *testing.T) {
-	err := MustBeOneBus("amqps://broker:5671/", "nats://bus:4222")
-	if err == nil {
-		t.Fatal("a control plane told about both buses was allowed to start")
-	}
-	// The remedy is in the words, because whoever reads this has to choose one and the wrong choice
-	// is a rollout half done.
-	for _, want := range []string{AMQPVarName, NATSVar, "unset"} {
-		if !strings.Contains(err.Error(), want) {
-			t.Errorf("the refusal does not mention %s: %v", want, err)
-		}
-	}
-}
-
-// One bus, or none, is ordinary. None is a control plane that publishes nothing and holds records,
-// which several of its own commands are.
-func TestOneBusOrNeitherIsAllowed(t *testing.T) {
-	for _, c := range []struct{ what, amqp, nats string }{
-		{"the bus the mesh runs on today", "amqps://broker:5671/", ""},
-		{"the bus being built", "", "nats://bus:4222"},
-		{"neither", "", ""},
-		{"neither, with whitespace for an address", "  ", "\t"},
-	} {
-		if err := MustBeOneBus(c.amqp, c.nats); err != nil {
-			t.Errorf("%s was refused: %v", c.what, err)
-		}
-	}
-}
 
 // The controller's own credential arrives in its address, and has to be readable out of it — its user
 // is created by the installer at a bootstrap password, before the controller exists to mint one.