Revert "Reland "[infra] Add failing test to test CI systems and approvals workflow""

This reverts commit c716068538cf25b32c396b2890d40192d804208e.

Reason for revert: Trying again to diagnose failure to copy approvals.

Original change's description:
> Reland "[infra] Add failing test to test CI systems and approvals workflow"
> 
> This reverts commit 25def20f5d6a5fecb54d6f85b353de49aeb37bd8.
> 
> Reason for revert: Retrying, now that we are copying CQ approvals for all commits in the blamelist of a builder.
> 
> Original change's description:
> > Revert "[infra] Add failing test to test CI systems and approvals workflow"
> > 
> > This reverts commit e578eeb235a178d6c93482026f66cf6bc1a694c7.
> > 
> > Reason for revert: The reverted commit is a test of the new approvals UI for tryjobs and the CI. It includes an intentionally failing test, that we now remove again.
> > 
> > Original change's description:
> > > [infra] Add failing test to test CI systems and approvals workflow
> > > 
> > > The failing test lib_2/collection/failing_list_test.dart is added,
> > > which imports dart:io.  So it will be a compile-time failure on
> > > some dart2js platforms, and a run-time failure on dart:io.
> > > 
> > > This commit is just to test the UI and backend for test failure
> > > approvals on tryjobs and on CI results. It will be reverted after
> > > the CI builders have run on it.
> > > 
> > > Change-Id: Icc3d11e72511cb0dbd9a62cb4fa80e754c203c8c
> > > Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/127883
> > > Reviewed-by: Jonas Termansen <sortie@google.com>
> > 
> > TBR=whesse@google.com,sortie@google.com
> > 
> > Change-Id: I32b900e25dc562ac88f5cb496cdbca726fc70445
> > No-Presubmit: true
> > No-Tree-Checks: true
> > No-Try: true
> > Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/127885
> > Reviewed-by: William Hesse <whesse@google.com>
> 
> TBR=whesse@google.com,sortie@google.com
> 
> Change-Id: I64e528131c779c8d20c007ff715b57b599cd3f07
> No-Presubmit: true
> No-Tree-Checks: true
> No-Try: true
> Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/127886
> Reviewed-by: William Hesse <whesse@google.com>
> Reviewed-by: Jonas Termansen <sortie@google.com>

TBR=whesse@google.com,sortie@google.com,athom@google.com

Change-Id: Icf68fd813d5f8f98d5ebf40c34e35811e8fffaf5
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/127892
Reviewed-by: William Hesse <whesse@google.com>