Gridap forces Dirichlet functions to be defined in the interior of the domain

It seems that functions defining Dirichlet boundaries are not evaluated just on the given boundary, but in all points of the elements, which have a point on any Dirichlet boundary. This behavior makes some implementation more complicated. Simple code describing the issue is attached

[DirichlerForces.zip](https://github.com/gridap/Gridap.jl/files/7348158/DirichlerForces.zip)