Reduce embedding container size

- Remove unnecessary dependencies from the [unstructured](https://github.com/Unstructured-IO) package (It seems not to be possible for now)
- Switch to Graviton (ARM builds seem to reduce image size. Need to validate)

Start by locating the embedding container definition and its dependency declarations, then measure the current image size. Investigate whether the unstructured package dependencies can be reduced and compare a Graviton ARM build; done means a validated reduction in container size, but the payload names no files or tests.

Written by the indexing model from the issue text.