Disables INFO level log messages in tests, including GL errors.

Bug: angleproject:3525
Change-Id: Ib16871b9faaff54964dd2770e1791372b1b79361
Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/1656293Reviewed-by: Jamie Madill <jmadill@chromium.org>
Commit-Queue: James Dong <dongja@google.com>