default to primary tablet if not set
default to primary tablet if not set

Signed-off-by: Harshit Gangal <af4d8fd3e8a94e9e7874ee31a198463039323a54@planetscale.com>
Signed-off-by: Florent Poinsard <3ed0b581b0418fb64e36dc5b436646200f1f1df7@outlook.fr>

tinyspeck/vitess,tinyspeck/vitess,tinyspeck/vitess,tinyspeck/vitess,tinyspeck/vitess,tinyspeck/vitess,tinyspeck/vitess