Now that we've introduced multiple change sources in the Review Changes module we should pass the feed origin into the instrumentation so that we can interrogate the click through rate on the separate link types.
Acceptance Criteria:
- Update instrumentation code in WikimediaEvents to differentiate an existing high risk diff link click from a watched page diff click. This can probably be done by just updating the element_friendly_name field depending on the source. That way we can still use the standard ClickThroughRateInstrument.
- Make sure this change is documented in our instrumentation spec