test: update testUpdateChannelPolicy to ensure Bob's link uses the proper policies

In this commit, we update the testUpdateChannelPolicy to exercise the
recent set of changes within the switch. If one applies this test to a
fresh branch (without those new changes) it should fail. This is due to
the fact that before, Bob would attempt to apply the constraints of the
incoming link (which we updated) instead of the outgoing link. With the
recent set of changes, the test now properly passes.

rpcserver.go

@@ -3331,7 +3331,7 @@ func (r *rpcServer) UpdateChannelPolicy(ctx context.Context,
 		TimeLockDelta: req.TimeLockDelta,
 	}
 
-	rpcsLog.Tracef("[updatechanpolicy] updating channel policy base_fee=%v, "+
+	rpcsLog.Debugf("[updatechanpolicy] updating channel policy base_fee=%v, "+
 		"rate_float=%v, rate_fixed=%v, time_lock_delta: %v, targets=%v",
 		req.BaseFeeMsat, req.FeeRate, feeRateFixed, req.TimeLockDelta,
 		spew.Sdump(targetChans))