[clang][ci] Don't block all jobs on clang-format

It was expressed in some reviews that Clang folks didn't want to hold
off other testing jobs in case clang-format failed. This patch makes
it so that the basic clang testing jobs will run even if clang-format
fails on the patch. The overall build will still be marked as failed,
but it will be possible to see the failures in clang tests so at least
there will be some feedback available.

The whole pipeline was originally blocked on clang-format because we
inherited that pipeline definition from libc++, where we want to block
on clang-format for capacity reasons.

Differential Revision: https://reviews.llvm.org/D159197

Author: ldionne

clang/utils/ci/buildkite-pipeline.yml

@@ -20,7 +20,6 @@ steps:
   - label: "Format"
     commands:
       - "clang/utils/ci/run-buildbot check-format"
-
     agents:
       queue: "linux"
     retry:
@@ -29,8 +28,6 @@ steps:
           limit: 2
     timeout_in_minutes: 120
 
-  - wait
-
   - label: "Building and testing clang (Linux)"
     commands:
       - "clang/utils/ci/run-buildbot build-clang"