Fix disable CSS preprocessing spelling

[hownowstephen]

Summary

• Fix the transactional email field spelling to disable_css_preprocessing
• Remove the misspelled disable_css_preproceessing keyword and JSON field

Tests

• PYTHONPATH=/private/tmp/customerio-python-deps /Users/stephen/.cache/codex-runtimes/codex-primary-runtime/dependencies/python/bin/python3 -m unittest discover -v

[cursor]

Cursor Bugbot has reviewed your changes and found 1 potential issue.

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