bjk-compression_threshold.yml

Lower the minimum size required for nginx to compress responses.
* Reduce the number of requests that need more than one packet. For
example, small json respones, `realtime_changes` respones, small raw
blobs.
* For gitlab.com, our CDN compresses requests of this size.

https://gitlab.com/gitlab-com/gl-infra/infrastructure/-/issues/10073



Signed-off-by: Ben Kochie <bjk@gitlab.com>