Revert "Reland "Pass buildername to devicelab test runner""

This reverts commit 3c3b498f3c78a5d80fd42a1390f3e91743ccaedd.

Reason for revert: Breaks release branch try jobs

Original change's description:
> Reland "Pass buildername to devicelab test runner"
>
> Original: https://flutter-review.googlesource.com/c/recipes/+/8660
>
> Bug: https://github.com/flutter/flutter/issues/66191
> Test: CQ
> Change-Id: Iaf686f35877656b0b0f732a6238efe254821537c
> Reviewed-on: https://flutter-review.googlesource.com/c/recipes/+/8846
> Reviewed-by: Keyong Han <keyonghan@google.com>
> Commit-Queue: Casey Hillers <chillers@google.com>

TBR=keyonghan@google.com,chillers@google.com,flutter-scoped@luci-project-accounts.iam.gserviceaccount.com

Change-Id: I1edee6d2ff26035c15c98e2fb3a3611c96379a30
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Bug: https://github.com/flutter/flutter/issues/66191
Reviewed-on: https://flutter-review.googlesource.com/c/recipes/+/8860
Reviewed-by: Casey Hillers <chillers@google.com>
Commit-Queue: Casey Hillers <chillers@google.com>