Fixed doxygen excluded files and path stripping

[m-fila]

BEGINRELEASENOTES

• Fixed doxygen excluded files and path stripping

ENDRELEASENOTES

The documentation generated with doxygen included tests and scripts which aren't part of exposed API

Broken file striping illustration with edm4hep::Vector3f docs:
Was:

edm4hep::Vector3f Class Reference

#include </builds/key4hep/edm4hep/edm4hep/edm4hep/Vector3f.h>
.
.
.
The documentation for this class was generated from the following file:

   - edm4hep/edm4hep/Vector3f.h

fixed:

edm4hep::Vector3f Class Reference

#include <edm4hep/Vector3f.h>
.
.
.
The documentation for this class was generated from the following file:

   - edm4hep/Vector3f.h

[tmadlener]

Thanks for fixing this.