Changes to Delete a slot of a Parents' Evening

removed the success response with the status 200

api operation id PanopticApiEndpointsParentsEveningSetupDeleteParentsEveningSlotEndpoint removed and replaced with PanopticApiEndpointsParentsEveningSetupDeleteSlotEndpoint

for the path request parameter slotId, the type was generalized from integer to string, and format from int32 to guid

added the non-success response with the status 404

added the non-success response with the status 409