swarming: support overriding default bot_id and task_id in test_api.
swarming: support overriding default bot_id and task_id in test_api.

R=vadimsh

Recipe-Nontrivial-Roll: fuchsia
Change-Id: Iaced87bbd6d79a729cba8106e0aed270f40df6ec
Reviewed-on: https://chromium-review.googlesource.com/c/infra/luci/recipes-py/+/1846934
Reviewed-by: Vadim Shtayura <9f116ddb1b24f6fc1916a676eb17161b6c07dfc1@chromium.org>
Reviewed-by: Marc-Antoine Ruel <d2bf0fc09b08f7b0888b3ddab32b3e89c7122c8b@chromium.org>
Commit-Queue: Andrii Shyshkalov <a30c74fa30536fe7ea81ed6dec202e35e149e1fd@google.com>
Auto-Submit: Andrii Shyshkalov <a30c74fa30536fe7ea81ed6dec202e35e149e1fd@google.com>

luci/recipes-py,luci/recipes-py