Comments: reduce activity log spam from WPML translations

This is a feature request from a user who is using WPML for English, Arabic, and Turkish translations on their site. The Activity Log is spammed any time a translated page with a Jetpack comment form is viewed. The activity log indicates there is a Server change to the Comments "Greeting Text" setting under `wp-admin/options-discussion.php`.

User report: 6497944-zd-woothemes

This value does not appear to be changing in the database and always shows as "Leave a Reply". This is an example of what the user sees: 

WPML support stated the following:

> Essentially, WPML is only serving the version of that text for the language requested, but it is the same text, it's not changing in the DB every time, the issue is that Jetpack detects that as if the text was changed. Jetpack is detecting as if it is a new text, even though it is the same text stored the first time you translated it. This change would have to be made inside Jetpack code.

The report points to wp-admin/options-discussion.php and the Activity Log, but names no Jetpack source file or test. Start by locating the code that detects the Comments “Greeting Text” server change and reproduce the WPML language-switching case; done means repeated page views no longer create false change entries while genuine setting changes remain logged.

Written by the indexing model from the issue text.