Remove HipChat project service
HipChat was recently acquired by Atlassian, and then by Slack. The result is that all HipChat users are being migrated to Slack. People using the self-hosted "HipChat Server" and "HipChat Data Center" products are not being automatically migrated, but Atlassian are withdrawing support, turning off the marketplace and removing the ability to add new users in 2019/2020. A full list of EOL dates are here: https://www.atlassian.com/partnerships/slack/faq#faq-2013ca70-3170-4a82-9886-03234e7084c0
Existing groups will be able to continue to add users and use Stride and Hipchat Cloud products until February 15th, 2019. Existing Hipchat Data Center & Hipchat Server customers will have support through the end of their license period.
In short, I think this means we should remove the HipChat integration from GitLab. This will also allow us to close ~20 other issues that relate to HipChat integration. We could do this any time, but certainly not later than the last EOL date for HipChat Data Center (2020), and probably around Feb 2019.
Removing the code and the HipChat gem is easy; removing any existing
HipchatService rows from the database is slightly harder.