core: Remove IsVdsWithSameHostExistsQurey

This patch removes the unused IsVdsWithSameHostExistQuery.

Removed in this patch:
1. The IsVdsWithSameHostExistQuery class.
2. The IsVdsWithSameHostExistParameters class only used by the
   aforementioned query.
3. The IsVdsWithSameHostExist constant from VdcQueryType corresponding
   to the aforementioned query.
4. The isVdsWithSameHostExists and isVdsWithSameHostExsitsStatic methods
   in VdsHandler which are no longer in use.

Change-Id: If6387786899342cf1c9e242aded0ee56053604bc
Signed-off-by: Allon Mureinik <amureini@redhat.com>