Ravi: can you add "memory.cluster_telemetry" to the default list of ct benchmark?

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/ac022645c53b0b32c816e7d426ddb5d3c006e648

commit ac022645c53b0b32c816e7d426ddb5d3c006e648
Author: Ned Nguyen <nednguyen@google.com>
Date: Fri Feb 23 00:59:55 2018

Add memory.cluster_telemetry benchmark

Bug:  814869 
Change-Id: I1ac86869acebcacef37788d5db3727b6dafeb1be
Reviewed-on: https://chromium-review.googlesource.com/932446
Commit-Queue: Ned Nguyen <nednguyen@google.com>
Reviewed-by: Ravi Mistry <rmistry@chromium.org>
Reviewed-by: Erik Chen <erikchen@chromium.org>
Cr-Commit-Position: refs/heads/master@{#538644}
[modify] https://crrev.com/ac022645c53b0b32c816e7d426ddb5d3c006e648/tools/perf/contrib/cluster_telemetry/OWNERS
[add] https://crrev.com/ac022645c53b0b32c816e7d426ddb5d3c006e648/tools/perf/contrib/cluster_telemetry/memory_ct.py
[modify] https://crrev.com/ac022645c53b0b32c816e7d426ddb5d3c006e648/tools/perf/validate_wpr_archives

The following revision refers to this bug:
  https://skia.googlesource.com/buildbot/+/3538e885f28b6387fcdee273bdcb879c0266e590

commit 3538e885f28b6387fcdee273bdcb879c0266e590
Author: Ravi Mistry <rmistry@google.com>
Date: Fri Feb 23 12:47:44 2018

[CT] Add new memory benchmark to list of supported benchmarks

Bug:  chromium:814869 
Change-Id: I84a14cb96d79f5d523151e22a1e5c108a03297fb
Reviewed-on: https://skia-review.googlesource.com/109760
Reviewed-by: Ravi Mistry <rmistry@google.com>
Commit-Queue: Ravi Mistry <rmistry@google.com>

[modify] https://crrev.com/3538e885f28b6387fcdee273bdcb879c0266e590/ct/go/util/constants.go

Thanks Ravi!