Bug 1093602 - Remove LogShake feature from v2.1 r=janx

The Gecko code for LogShake feature only landed in master. So we should
rather remove the Gaia exposition of this to avoid confusion for users
and developpers.
Merge pull request #25806 from lissyx/bug1093602

Bug 1093602 - Remove LogShake feature from v2.1 r=janx