[Sampling profiler] Enable reporting by default

Reporting has been enabled at 100% server-side for ages. This flips the
client default so we can avoid sending the experiment state.

Change-Id: I2c88ce73fbf23c83e4572d9db3c72bbda28a8243
Reviewed-on: https://chromium-review.googlesource.com/c/1351379
Reviewed-by: Alexei Svitkine <asvitkine@chromium.org>
Commit-Queue: Mike Wittman <wittman@chromium.org>
Cr-Commit-Position: refs/heads/master@{#611181}