With a speeding ticket in California, is it legal for the officer to
list your race without asking you?

Race as used by police depts. is for visual identification.  If
someone looks white, but is of Hispanic origin, white would be the
correct classification, as it would be most helpful in identifying a
person.

If you earned the ticket, go ahead and pay it and don't speed again.

Nobody questions the legality of listing a person's hair or eye color
on various documents that ask for a description of a person.  Not that
I know of anyway.