Revert "builds-api: use the non-deprecated heroku builder"
We can't use the newer lifecycle until we update the apt buildpack to the buildpack API >=0.6
This reverts commit 535b5ea8.
How to register an account on GitLab. Due to spam, new accounts are locked until approved by an admin or the approver bot. Your GitLab account gets automatically approved within one hour if you are a member of Trusted Contributors in Gerrit, or a member of the Trusted-Contributors group in Phabricator and linked your Developer account to your Phabricator account. If none of these apply, you can file an unlock request to expedite access.
Support: mw:GitLab, how to host a project on GitLab, #wikimedia-gitlab on libera.chat, #GitLab on Phabricator.
We can't use the newer lifecycle until we update the apt buildpack to the buildpack API >=0.6
This reverts commit 535b5ea8.