A recurring event with a start date and a time duration had a wrong start and
stop date computed.
Introduced at 76b724294a.
Previously the r_date contained only the start_date but now it contains both
start and stop dates. This implies that the method 'get_recurrent_ids' could
use 'get_search_fields' with a stop_date (depending on the domain order) and
returns incorrect dates.
This commit ensure to launch the get_search_fields with the start date.
Closes#15922
amoyaux
447356f7ee