feat: update nitro-testnode, name DA container celestia-da

[jcstein]

Overview

This resolves an underlying issue with nitro-testnode, on the default setup in documentation, so that developers have a standard name for the Celestia DA container, as celestia-da.

WIP: to be merged after:

• fix: give container name to resolve discrepancies between different docker builds nitro-testnode#5
• changing back the submodule to the celestiaorg/nitro-testnode version

Checklist

• New and updated code has appropriate documentation
• New and updated code has new and/or updated testing
• Required CI checks are passing
• Visual proof for any user facing features like CLI or documentation updates
• Linked issues closed with keywords

[jcstein]

closing and will have @Ferret-san update commit of nitro-testnode on blobstream-develop branch of Nitro, once this is merged celestiaorg/nitro-testnode#10