Migrate build/upload Elastic Beanstalk artifact code into main release script...

Migrate build/upload Elastic Beanstalk artifact code into main release script and other improvements (#13635)

* Always use current branch; determine CE vs EE build based on version number

* Rename delete-file! -> delete-file-if-exists!

* Dox & TODO message

* Move draft release template

* Some logging tweaks for deleting files

* Move s3 upload code to common namespace

* Integrate EB artifact logic

* Move .ebextensions -> release

* Remove old EB release scripts