[node] Make `GetChunks` compatible with minibatches

[ian-shim]

Why are these changes needed?

Make chunk retrieval compatible with minibatches. If the retrieval with previous schema fails, it tries with the new schema.

To be merged on top of https://github.com/Layr-Labs/eigenda/pull/698

Checks

• [ ] I've made sure the lint is passing in this PR.
• [ ] I've made sure the tests are passing. Note that there might be a few flaky tests, in that case, please comment that they are not relevant.
• Testing Strategy
  • [ ] Unit tests
  • [ ] Integration tests
  • [ ] This PR is not tested :(