Deployment tier guesses incorrect tier for string 'nonprod'

Summary

Deployment tiers are determined based on a regex of the deployment name. The strings prod or production will be linked to the production deployment tier. The regex incorrectly wraps nonprod as a production tier.

Steps to reproduce

A job created with the following parameters in the .gitlab-ci.yml will mark nonprod as a production tier:

deploy_nonprod:
  stage: staging
  script:
    - echo "Deploy to non-production server"
  environment:
    name: nonprod
    url: https://example.com
  rules:
    - if: $CI_COMMIT_BRANCH == $CI_DEFAULT_BRANCH
      when: manual

What is the current bug behavior?

The string nonprod is marked as a production tier.

What is the expected correct behavior?

The string nonprod should be marked as staging or testing.

Output of checks

Results of GitLab environment info

Expand for output related to GitLab environment info

(For installations with omnibus-gitlab package run and paste the output of:
`sudo gitlab-rake gitlab:env:info`)

(For installations from source run and paste the output of:
`sudo -u git -H bundle exec rake gitlab:env:info RAILS_ENV=production`)

Results of GitLab application Check

Expand for output related to the GitLab application check

(For installations with omnibus-gitlab package run and paste the output of:
sudo gitlab-rake gitlab:check SANITIZE=true)
(For installations from source run and paste the output of:
sudo -u git -H bundle exec rake gitlab:check RAILS_ENV=production SANITIZE=true)
(we will only investigate if the tests are passing)

Possible fixes

Change the following regex to exclude nonprod:

https://gitlab.com/gitlab-org/gitlab/-/blob/v15.4.2-ee/app/models/environment.rb#L545