Reorder GitLab.com Reliability biggest risk

Why is this change being made?

This MR updates the company's biggest risk page moving GitLab.com Reliability from risk 26 to risk 11. In this MR only ordering of risks are modified.

Below is some additional context describing the reasoning for this change.

Since 2016 the number of builds run on GitLab.com has been increasing exponentially, doubling roughly every 8 months. From 2016 through 2020 roughly 1 Billion CI builds were run on GitLab.com. We project the next 1 Billion will be run in the next 9 month (possibly sooner if our GTM momentum continues to accelerate). Currently we trigger roughly 24 customer builds per second and this will continue to accelerate exponentially (we hope). Scaling a system at this rate is no simple task and many things that used to work will start to break down and be rearchitected as our scale continues to increase. It will be necessary to stay ahead of our rapidly accelerating data volume and scale to avoid disruption to GitLab.com's availability.

• From recent Verify Stage team day some slides illustrating this growth Slide 4 - CI builds created per month. Currently ~60M/month or ~24/sec “https://docs.google.com/presentation/d/1MKrCNr6TDEvZux4lOE8PwZIJrRJyQFpEQiYYisozllw/edit#slide=id.gbddfebace6_0_1
• Slide 5 - Historical and projected cumulative growth of CI builds, illustrating when we can may run out of primary keys on CI build table. ~1B jobs run from 2016-2020. We anticipate hitting 2B late this year (though it is possible this will accelerate) https://docs.google.com/presentation/d/1MKrCNr6TDEvZux4lOE8PwZIJrRJyQFpEQiYYisozllw/edit#slide=id.gbddfebace6_0_7

Author Checklist

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• Added a description to this MR explaining the reasons for the proposed change, per say-why-not-just-what
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