Before this commit, the report Leave Summary had hr.leave as its model
implicitly meaning that a report could be printed from an hr leave.
Since the report actually is a view which aggregates data, and not a document
representing a leave, it should have its wizard (the only entry point for that report)
as its model
OPW 2029699
closes odoo/odoo#34507
Signed-off-by: Lucas Perais (lpe) <lpe@odoo.com>