Update Tenant Scale error budget exception

Why is this change being made?

The Tenant Scale team continues to lack the capacity to focus on improving their error budget while they focus on delivering key pieces of the Cells project.

For some context, see previous discussions in gitlab-com/www-gitlab-com!108039 (merged) and gitlab-com/www-gitlab-com!121190 (merged).

The tradeoff for not renewing this exception would be slower progress on Cells, a long-term scalability effort for which the team is already understaffed. That said, we have seen an improvement over the last month in the team's error budget (99.84% last 28d and 99.85% last 7d), possibly due to rate limits recently introduced (https://about.gitlab.com/blog/2024/05/14/rate-limitations-announced-for-projects-groups-and-users-apis/).

Author and Reviewer Checklist

Please verify the check list and ensure to tick them off before the MR is merged.

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Commits

• Update Tenant Scale error budget exception

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