[Feature flag] Enable Design Management resizing of designs

What

Remove the :design_management_resize_images feature flag added in !22860 (merged).

Owners

• Team: Create:Knowledge
• Most appropriate slack channel to reach out to: #g_create_knowledge
• Best individual to reach out to: @.luke

Expectations

### What are we expecting to happen?

Designs that are uploaded to Design Management will have smaller versions generated.

What might happen if this goes wrong?

• Sidekiq memory could be negatively impacted
• Sidekiq CPU could be negatively impacted
• NewVersionWorker could start erroring

What can we monitor to detect problems with this?

• Sentry for Sidekiq errors
• Grafana Sidekiq Stats dashboard
  • CPU usage
  • Memory usage
  • Exception rate
• Grafana redis-sidekiq folderredis-sidekiq: Overview dashboard
  • Memory used
  • Memory saturation
  • CPU per node
• Grafana Sidekiq servicesidekiq: Overview dashboard
  • Saturation details

Beta groups/projects

If applicable, any groups/projects that are happy to have this feature turned on early. Some organizations may wish to test big changes they are interested in with a small subset of users ahead of time for example.

• gitlab-org/gitlab project
• gitlab-org/gitlab-com groups

Roll Out Steps

• Enable on staging
• Test on staging
• Ensure that documentation has been updated - The only relevant documentation is the auto-generated GraphQL docs
• Enable on GitLab.com for individual groups/projects listed above and verify behaviour
• Coordinate a time to enable the flag with #production and #g_delivery on slack.
• Announce on the issue an estimated time this will be enabled on GitLab.com
• Enable on GitLab.com by running chatops command in #production
• Cross post chatops slack command to #support_gitlab-com and in your team channel
• Announce on the issue that the flag has been enabled
• Remove feature flag and add changelog entry
• After the flag removal is deployed, clean up the feature flag by running chatops command in #production channel