try -O1 to speed up msan bot

We want it to be a debug build, but it probably doesn't need to be
completely unoptimized.

dm: 27m -> 7m
nanobench: 140m -> 33m

BUG=skia:
GOLD_TRYBOT_URL= https://gold.skia.org/search2?unt=true&query=source_type%3Dgm&master=false&issue=1678693002

CQ_EXTRA_TRYBOTS=client.skia:Test-Ubuntu-GCC-GCE-CPU-AVX2-x86_64-Debug-MSAN-Trybot

Review URL: https://codereview.chromium.org/1678693002
1 file changed