Unicorn: raise defaults for memory killer

Summary

The charts default to what appear to be the defaults in the Omibus GitLab, of 400/650 (see #1025 (closed)). These may be too low, resulting in the worker processes being reaped more often than necessary.

GitLab.com sets:

unicorn['worker_memory_limit_min'] = 786432000
unicorn['worker_memory_limit_max'] = 1073741824

Further info, see

• gitlab-org/omnibus-gitlab#4279 (closed)
• https://gitlab.com/gitlab-org/gitlab-ee/issues/11198#note_161870577

Versions

• Chart: 1f7d224d
• Platform: N/A

Relevant logs

See linked issues

cc @stanhu @abuango