Do not configure multitenantcy flag in Bus builders

[alexander-yevsyukov]

... take it from a BoundedContext into which the bus is inserted.

A bus cannot have a different setting. So there's no sense in the API for configuring it in a builder.

[armiol]

At this point it's only present in CommandBus.Builder and used later to ensure that a Command posted to a multitenant CommandBus has a tenant ID set.