When Sentry gets Rack context, it can grab information that is very
large (like Grape routing information) from the Rack environment. It can
waste a lot of time and memory processing that information, only to then
... not send it to Sentry as it's not a standard key.

https://github.com/getsentry/sentry-ruby/pull/1197 describes this
perfectly, but as we're not on the latest version,
https://github.com/getsentry/sentry-ruby/pull/1198 is the PR that we're
pulling in to fix this issue.

To test this locally:

1. Create a project.
2. Move or delete its on-disk repo.
3. Configure Sentry.
4. Run `curl http://$host/api/v4/projects/$id/repository/branches/main`.
5. Check the `mem_bytes` field in `api_json.log`.

This change takes several hundred megabytes from that value in my local
environment.

Changelog: performance