Remove memory.long_running_idle_gmail* benchmarks

Bug: 938937
Change-Id: I7326f03b28d50a826552c8b1335989daa7ed0f44
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1506078
Reviewed-by: Emily Hanley <eyaich@chromium.org>
Commit-Queue: Ulan Degenbaev <ulan@chromium.org>
Cr-Commit-Position: refs/heads/master@{#638566}
19 files changed