[MRG] Optimize Dockerfiles

[joaquingx]

Description

• Update dockerfiles.

Issue

• Github Issue ID.

Checklist before requesting a review

• I have performed a self-review of my code.
• My code follows the style guidelines of this project.
• I have made corresponding changes to the documentation.
• New and existing tests pass locally with my changes.
• If this change is a core feature, I have added thorough tests.
• If this change affects or depends on the behavior of other estela repositories, I have created pull requests with the relevant changes in the affected repositories. Please, refer to our official documentation.
• I understand that my pull request may be closed if it becomes obvious or I did not perform all of the steps above.

[mgonnav]

@joaquingx I have optimized the Dockerfiles, drastically reducing the Dockerfile sizes and improving security. The changes I integrated yield the following improvements in Dockefile sizes:

• estela-django-api: 1.25GB -> 373MB
• estela-celery-beat: 1.25GB -> 373MB
• estela-celery-worker: 1.25GB -> 373MB
• estela-build-project: 1.65GB -> 879MB
• queue-consumer: 1.04GB -> 210MB

I have tested deploying a project and running a couple of jobs with the updated Dockefiles, and it has worked fine for me. Please also test it on your side.