feat(backend): Remove distillery for releases

[davidspek]

Summary

To unblock #806, this PR aims to remove distillery since it is not maintained and can be replaced by mix release instead.

Useful references:

• https://blog.thecraftingstrider.net/posts/tech/2020.01/migrate-to-elixir-releases/
• https://hexdocs.pm/mix/Mix.Tasks.Release.html
• https://elixirschool.com/blog/releasing-an-umbrella-app-with-docker-and-mix-release

Test Plan

Build images with mix release and test that those work as expected.

Checklist

• If required, I have updated the Plural documentation accordingly.
• I have added tests to cover my changes.
• I have added a meaningful title and summary to convey the impact of this PR to a user.
• I have added relevant labels to this PR to help with categorization for release notes.

[stoat-app]

Easy and customizable dashboards for your build system. Learn more about Stoat ↗︎

Static Hosting

Name	Link	Commit	Status
api-coverage	Visit	2a0c651	✅
rtc-coverage	Visit	2a0c651	✅
core-coverage	Visit	2a0c651	✅
cron-coverage	Visit	2a0c651	✅
email-coverage	Visit	2a0c651	✅
worker-coverage	Visit	2a0c651	✅
api-test-results	Visit	2a0c651	✅
graphql-coverage	Visit	2a0c651	✅
rtc-test-results	Visit	2a0c651	✅
core-test-results	Visit	2a0c651	✅
cron-test-results	Visit	2a0c651	✅
email-test-results	Visit	2a0c651	✅
worker-test-results	Visit	2a0c651	✅
graphql-test-results	Visit	2a0c651	✅

Job Runtime