Further reduce the number of primitives in the donut tests. Avoids crashes on iOS.

BUG=skia:4937
GOLD_TRYBOT_URL= https://gold.skia.org/search2?unt=true&query=source_type%3Dgm&master=false&issue=1691813002

Review URL: https://codereview.chromium.org/1691813002
1 file changed