Fix generate_kwargs logic for TiledAutomaticPromptGenerator

[titusgriebel]

@anwai98
This fixes #1202
TiledAutomaticPromptGenerator seems to be the only segmenter having an issue with tile_shape and halo, so this should be it.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 20.34%. Comparing base (6ad8238) to head (7ff7066).
⚠️ Report is 719 commits behind head on master.

Additional details and impacted files

@@             Coverage Diff             @@
##           master    #1203       +/-   ##
===========================================
- Coverage   39.80%   20.34%   -19.47%     
===========================================
  Files          33       48       +15     
  Lines        4185     6814     +2629     
===========================================
- Hits         1666     1386      -280     
- Misses       2519     5428     +2909     

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