[resultdb] Added logging in invocations.Reachable
[resultdb] Added logging in invocations.Reachable

Added temporary logging to diagnose crbug.com/1110219

Bug: 1110219
Change-Id: Ic78a248d5f7cade7489bb9062278eebbed84dc35
Reviewed-on: https://chromium-review.googlesource.com/c/infra/luci/luci-go/+/2325420
Auto-Submit: Nodir Turakulov <ef4933a197ef7b4b3f55f1bec4942aead3637a2a@chromium.org>
Commit-Queue: Vadim Shtayura <9f116ddb1b24f6fc1916a676eb17161b6c07dfc1@chromium.org>
Reviewed-by: Vadim Shtayura <9f116ddb1b24f6fc1916a676eb17161b6c07dfc1@chromium.org>

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