Investigation: Can we refactor indexer integration tests to be deterministic?

## Problem

Formerly a comment found in #192 :

> # A potential improvement space:
> # we can make this test determinstic (i.e., removing sleep for indexer) by waiting indexer to be at the same round of algod finishing all the box operations.
> # Once indexer has a round number at least as large as algod finishing box operations, the changes on boxes can be reflected in indexer side.

This is a useful improvement, and more generally, **full determinism** in integration tests would lead to easier test creation.

## Dependencies

None

## Urgency

Low - tests are working fine as they are currently designed.