This reverts commit dbce02f6.

Reason for revert:
Breaking cq presubmit step

Original issue's description:
> Update third_party/checkstyle to 7.6.1
>
> This CL updates third_party/checkstyle to 7.6.1 so checkstyle would
> work with Java 8 lambda features.
>
> BUG=703238
>
> Review-Url: https://codereview.chromium.org/2799303003
> Cr-Commit-Position: refs/heads/master@{#462968}
> Committed: https://chromium.googlesource.com/chromium/src/+/dbce02f63421f7d446d6ef317b456f6ae911f63b

TBR=agrieve@chromium.org,nyquist@chromium.org,jbudorick@chromium.org,klobag@chromium.org,jbudorick@google.com
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=703238

Review-Url: https://codereview.chromium.org/2807753003 .
Cr-Commit-Position: refs/heads/master@{#463021}