Revise Optimize GMAU Q4 target to 10% lift

Why is this change being made?

Previously, we didn't have a reliable GMAU for Optimize and we needed to validate the data we were collecting in usage ping. We've successfully validated the accuracy of the counter (analytics_unique_visits_for_any_target_monthly) and can set a target.

Since usage data only works moving forward (we can't go back in time and retroactively study any the impact of any counters added), so setting a target is challenging. In Product#1603 (comment 429240058), I pulled some data from Snowplow based on total pageviews; in that issue, I proposed making our goal +10%, which would put our numbers back around May - July levels and motivate us to research into the reason for the decline.

I propose setting our Q4 target to increase the number of unique users viewing analytics page to +10% of October's level, or about 40,150 unique viewers on SaaS.

This doesn't include self-managed data, since we're JUST seeing users upgrade after making a self-managed feature flag default-on. After we see more data from self-managed users, we'll adjust this goal accordingly.

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