fix: docker build on erlang 25

[nlwstein]

This PR attempts to solve the Docker build issue presenting on main by removing distillery.

Reason: bitwalker/distillery#744

The approach taken here is similar to this commit: mbta/concentrate@a9b4d57

It also adds a Docker build job to the Elixir workflow that runs on PRs.

[nlwstein]

@bklebe This PR is to address the failure that occurred when #215 was merged.

It may be worth a chat tomorrow to test this further locally, since it does rip out a part of the release process and I cannot test the image fully locally without some secrets I do not have currently loaded into env vars.

I am also going to go through and make sure each repo has it's Docker image building correctly as well, though at least half of the repos seem to already have a Docker image build on commit test.

[bklebe]

@nlwstein I would recommend a dev deploy to see if it boots at least.

[bklebe]

Just tried a dev deploy, looks good to me.