Change microbatch lookback default from 0 to 1

[QMalcolm]

Resolves #10867

Problem

A lookback value of 0 results in microbatch models consistently having incomplete data.

Solution

Change the lookback default to 1. This guarantees that batches will eventually get completed (assuming the job is run once per batch_size)

Checklist

• I have read the contributing guide and understand what's expected of me.
• I have run this code in development, and it appears to resolve the stated issue.
• This PR includes tests, or tests are not required or relevant for this PR.
• This PR has no interface changes (e.g., macros, CLI, logs, JSON artifacts, config files, adapter interface, etc.) or this PR has already received feedback and approval from Product or DX.
• This PR includes type annotations for new and modified functions.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 89.15%. Comparing base (8be0635) to head (36943f0).

Additional details and impacted files

@@            Coverage Diff             @@
##             main   #10876      +/-   ##
==========================================
- Coverage   89.18%   89.15%   -0.03%     
==========================================
  Files         183      183              
  Lines       23438    23438              
==========================================
- Hits        20903    20896       -7     
- Misses       2535     2542       +7     

Flag	Coverage Δ
integration	86.43% <100.00%> (-0.03%)	⬇️
unit	62.13% <100.00%> (ø)

Flags with carried forward coverage won't be shown. Click here to find out more.

Components	Coverage Δ
Unit Tests	62.13% <100.00%> (ø)
Integration Tests	86.43% <100.00%> (-0.03%)	⬇️

[QMalcolm]

Changes to schemas.getdbt.com dbt-labs/schemas.getdbt.com#68