early start zygote_secondary as well

- late start of zygote_secondary leads into occasional
  1 second wait for starting system service.
- Early start secondary zygote so that there is no additional
  wait.

bug: 37508384
Test: python packages/services/Car/tools/bootanalyze/bootanalyze.py -r -c packages/services/Car/tools/bootanalyze/config.yaml -n 100 -f -e 16 -w 30

(cherry picked from commit f8532445)

Change-Id: Ia46b07f3d6abb090cc169ebd807e21b16694d172