The optimization for the large trace perf tests was so costly that in
some configs it would fail to build at all. This could cause build
failures in the ANGLE CQ. Disable optimization to work around this
until we can isolate the compiler flags to just the trace perf tests.

Note: this only applies to the test harness. ANGLE itself is still
optimized in release builds by default.

Trace trimming would also help alleviate this problem. We could also
consider removing a few traces temporarily.

Bug: angleproject:3630
Change-Id: I2bd8fb76f330692aa715249ca8656965b5a29d8c
Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/2103674Reviewed-by: Jamie Madill <jmadill@chromium.org>
Commit-Queue: Jamie Madill <jmadill@chromium.org>