[particles] Turn on CI/CD for particles.skia.org

Add entry to cloudbuild.yaml

Bug: skia:
Change-Id: I649e42f3e4e97e33a673a816ba7815abe1bc08a7
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/200462
Reviewed-by: Joe Gregorio <jcgregorio@google.com>
1 file changed