infra: Increase shards for end2end tests on ASAN In preparation for https://chromium-review.googlesource.com/c/angle/angle/+/3671977 that adds more load on these bots. Bug: angleproject:5881 Change-Id: I505f1b1a75fb5c398dddfe2b8b4ef696b0298062 Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/3690744 Reviewed-by: Yuly Novikov <ynovikov@chromium.org> Commit-Queue: Shahbaz Youssefi <syoussefi@chromium.org>