[bazel] Use pre-built taskdriver for faster BazelBuild jobs

With a hot Bazel cache, https://task-scheduler.skia.org/job/4XhwJfG1wR38Hp3dF1pI
took 59 seconds and did not have to wait 1-2 minutes
for TaskScheduler to schedule a prerequisite task
and Swarming to deduplicate said task, which is
the best case scenario for "all hot caches".

Change-Id: Ic86599e0b886ecded836641cceb19b623065a91e
Bug: skia:12541
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/546136
Reviewed-by: Eric Boren <borenet@google.com>
4 files changed