This reverts commit 9e89a175.

This reverts commit b897039f.

Co-authored-by: Johan Lorenzo <jlorenzo@mozilla.com>

The mozilla-central ffmpeg toolchain (used in Bug 1613479/#8780) has an
artifact that does not start with `public/build/` (it starts with just
`public/`). To easily support that, we want to set the `toolchain-artfiact`
attribute for that task.

We switched `index_search` to be a job-type in
[taskgraph](https://hg.mozilla.org/ci/taskgraph/rev/932b4cf48cc785c31b03f0b9f2cba654bc67bc00)
which pass through `attributes` from the task definition (and is also more
future proof for adding fenix-specific toolchain tasks). This updates taskgraph
and the consumers of the current toolchain.

I think this should be all we need to support CoT for Fenix actions.

This patch removes `parameters` from the yml in favor of `push` based
on the taskgraph changes that need to happen.

* Bump taskgraph to latest revision

* Change Flank url

The repository moved from github.com/TestArmada/flank to
github.com/Flank/flank, and the curl command in the ui-tests Dockerfile
currently fails because of the redirection.

I'm sorry, Dave, I'm afraid I can't do that.

This reverts commit bd9ff938e79b0cabc5a142f18503284c3dfa3e4d.