[buildbucket] Add logs about batch requests' size
[buildbucket] Add logs about batch requests' size

Bug: 1144958
Change-Id: I5205fa9a96b80746e41c546e7897fbc8509899f2
Reviewed-on: https://chromium-review.googlesource.com/c/infra/luci/luci-go/+/2721363
Commit-Queue: Yuanjun Huang <a5f4b8445ce5e958d19c0a7caeadcd07c9d18770@google.com>
Reviewed-by: Nodir Turakulov <ef4933a197ef7b4b3f55f1bec4942aead3637a2a@chromium.org>
Reviewed-by: smut <95deb7aa15d4c615299e47e7688551456568b1fb@google.com>

luci/luci-go,luci/luci-go,luci/luci-go,luci/luci-go,luci/luci-go,luci/luci-go