purge_gs.sh: Remove reboot.

This shell script doesn't run with root privs, and so can't do a
reboot. I updated the startup script on the VM instances to do it
instead.

BUG=None
TEST=None

Change-Id: I333e4363bb605cf69bac81cdb7b2cd2724be0d39
Reviewed-on: https://chromium-review.googlesource.com/477117
Commit-Ready: Don Garrett <dgarrett@chromium.org>
Tested-by: Don Garrett <dgarrett@chromium.org>
Reviewed-by: Prathmesh Prabhu <pprabhu@chromium.org>
1 file changed