Remove redundant bool member for annotations param in RouteParameters

[karenzshea]

Given the work in #3628 which makes the annotations parameter for route and matching services accept an enum of individual values, including All and None, the boolean based annotations parameter can be removed from the interface. Needs to happen in v6 though because it is breaking.

[daniel-j-h]

And we should think about encapsulation. At least for our public API.
Otherwise we will hit this in the future again.