[swarming] fix taskqueue routing test
[swarming] fix taskqueue routing test

This is a minor test improvement and test only change.
- Use webapp2.Route.match instead of String.startswith
- Removed TODOs

Change-Id: I5d0e465e2c4859b9ae821f94f0378d4a5687fa15
Reviewed-on: https://chromium-review.googlesource.com/c/infra/luci/luci-py/+/1916995
Commit-Queue: Junji Watanabe <aaef61ef98ffea505db831f310be2a0eb8492537@google.com>
Auto-Submit: Junji Watanabe <aaef61ef98ffea505db831f310be2a0eb8492537@google.com>
Reviewed-by: Marc-Antoine Ruel <d2bf0fc09b08f7b0888b3ddab32b3e89c7122c8b@chromium.org>

luci/luci-py,luci/luci-py,luci/luci-py,luci/luci-py