services/galexie: Build and push galexie images on master commits

[travertischio]

PR Checklist

PR Structure

• This PR has reasonably narrow scope (if not, break it down into smaller PRs).
• This PR avoids mixing refactoring changes with feature changes (split into two PRs
  otherwise).
• This PR's title starts with name of package that is most changed in the PR, ex.
  services/friendbot, or all or doc if the changes are broad or impact many
  packages.

Thoroughness

• This PR adds tests for the most critical parts of the new functionality or fixes.
• I've updated any docs (developer docs, .md
  files, etc... affected by this change). Take a look in the docs folder for a given service,
  like this one.

Release planning

• I've reviewed the changes in this PR and if I consider them worthwhile for being mentioned on release notes then I have updated the relevant CHANGELOG.md within the component folder structure. For example, if I changed horizon, then I updated (services/horizon/CHANGELOG.md. I add a new line item describing the change and reference to this PR. If I don't update a CHANGELOG, I acknowledge this PR's change may not be mentioned in future release notes.
• I've decided if this PR requires a new major/minor version according to
  semver, or if it's mainly a patch change. The PR is targeted at the next
  release branch if it's not a patch change.

What

Update Makefile and Github actions workflows to build and push Galexie container images on all master commits in this repo

Why

We want to have regular master commit images in the dockerhub for Galexie for additional environments and eventually for retagging release images.

[urvisavla]

what stellar-core version is this docker image built with? you’ll need to set STELLAR_CORE_VERSION.

[travertischio]

thank you

35b047d

[urvisavla]

Are we going to periodically clean up those docker images we push on every master commit? They’re going to pile up. Have we considered pushing them to a private docker repo?

[travertischio]

we will definitely be pushing more images than we are right now
setting up automatic pruning in docker hub for this repository sounds like something we might do in the future

here is a link to some discussions that pushed us to use the public dockerhub repo in the design doc for these changes
https://docs.google.com/document/d/1dDRf6VCS_4iizjD_y4sKcPoHOh99-0jBDtn4rXdKrN8/edit?disco=AAABsNvBkAA