Disable sending KeyUpdates by default.

68df3afe5a62b4bb8f7ec57130f4e8e7002867e9 was intended to find buggy
servers that don't implement TLS 1.3 KeyUpdate correctly, and it didn't
take long to find some (see bug). This change disables sending
KeyUpdates by default until we've figured out those sites.

TBR=davidben@chromium.org

Bug: 923685
Change-Id: I44968fa85b2b92e18579e7d0fbd13b4b93ecffff
Reviewed-on: https://chromium-review.googlesource.com/c/1424419
Reviewed-by: Adam Langley <agl@chromium.org>
Commit-Queue: Adam Langley <agl@chromium.org>
Cr-Commit-Position: refs/heads/master@{#624492}
1 file changed