[bb] Init clients in bb batch
[bb] Init clients in bb batch

TBR=tandrii@chromium.org, 76cc7f10de6bc994d83c4cb09072e4590b82b709@chromium.org

Bug: v8:9102
Change-Id: Iab3e6152408e1ff8838f9ac28fa0c59133e91a5d
Reviewed-on: https://chromium-review.googlesource.com/c/infra/luci/luci-go/+/1559785
Reviewed-by: Nodir Turakulov <ef4933a197ef7b4b3f55f1bec4942aead3637a2a@chromium.org>
Reviewed-by: Michael Achenbach <76cc7f10de6bc994d83c4cb09072e4590b82b709@chromium.org>
Commit-Queue: Nodir Turakulov <ef4933a197ef7b4b3f55f1bec4942aead3637a2a@chromium.org>

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