Mode defining the behavior of the search, trading off latency
versus solution quality. In all modes, the global request
deadline is enforced.
Values:
SEARCH_MODE_UNSPECIFIED (0):
Unspecified search mode, equivalent to RETURN_FAST.
RETURN_FAST (1):
Stop the search after finding the first good
solution.
CONSUME_ALL_AVAILABLE_TIME (2):
Spend all the available time to search for
better solutions.