Fix Typos In Unit Tests

[mawelborn]

This PR fixes a couple typos in the unit test suite I found while checking the feature parity of the C# version. These don't change any test results or require publishing a new version.

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Note

Low Risk
Low risk: test-only typo fixes (span end index and fixture naming) with no production code changes.

Overview
Fixes typos in tests/etloutput/test_token_table_cell.py by correcting the line_item_span end offset and renaming the misspelled mulitple_table_span fixture (and its usage) to multiple_table_span.

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