[resultdb] Clone request before calling
[resultdb] Clone request before calling

In tests, clone the request before calling ReportTestResultsRequest
because the latter modifies the request.

Bug: 1177620
Change-Id: I30d76f2d06a1ab31fbc5c9eaca18b4c933a1898e
Reviewed-on: https://chromium-review.googlesource.com/c/infra/luci/luci-go/+/2704719
Reviewed-by: Scott Lee <1dcb292530f82960316cb3d87cd67c3f212b79cb@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