Set arroyo's max_pending_futures to 0

[NicoHinderling]

A simpler alternative to #512. Given how slow our average processing time is, we don't gain much performance benefit from the prefetching and this also solves the problem described in that PR.

The only downside of this approach is that if we set our consumer's concurrency > 1, arroyo may not use that extra concurrency because it wouldn't accept another pending future... so if we ever want to have concurrency > 1, we'll want to do the #512 approach, but we should be far away from needing to do that (and can just scale up the number of pods instead)

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 80.91%. Comparing base (1e64b6b) to head (da9fbdb).
⚠️ Report is 1 commits behind head on main.
✅ All tests successful. No failed tests found.

Additional details and impacted files

@@           Coverage Diff           @@
##             main     #513   +/-   ##
=======================================
  Coverage   80.91%   80.91%           
=======================================
  Files         164      164           
  Lines       14213    14213           
  Branches     1501     1501           
=======================================
  Hits        11500    11500           
  Misses       2144     2144           
  Partials      569      569           

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.

🚀 New features to boost your workflow:

• 📦 JS Bundle Analysis: Save yourself from yourself by tracking and limiting bundle sizes in JS merges.