* Update Shippable integration test groups.
* Update integration test group aliases.
* Rebalance AWS and Azure tests with extra group.
* Rebalance Windows tests with another group.
Fix 'task name is not templated in retry callback'
Add a task_name property to TaskResult that knows to
check in TaskResult._task_fields.
Add integration test for v2_retry_runner callback
Fixes#18236