[LibenHailu]

Fixes #40902

Description

This PR fixes two bugs in Beam YAML windowing transforms:

1. YamlProviders.WindowInto._parse_duration (yaml_provider.py):

   • Fixed the 'd' (day) time unit multiplier from 60 * 60 * 12 (43,200s / 12 hours) to 60 * 60 * 24 (86,400s / 24 hours).

2. _ExtractWindowingInfo (yaml_mapping.py):

   • named_fields_from_element_type(pcoll.element_type) returns list[tuple[str, type]], so elif field in existing_fields: was comparing a str against (str, type) tuples and always evaluated to False.
   • Extracted existing_field_names = {name for name, _ in existing_fields} and checked elif field in existing_field_names: so that colliding windowing field names properly raise ValueError(f'Input schema already has a field named {field}.').

Tests Added

• YamlWindowingTest.test_parse_duration and YamlWindowingTest.test_windowing_days in sdks/python/apache_beam/yaml/yaml_transform_test.py
• YamlMappingTest.test_extract_windowing_info_duplicate_field in sdks/python/apache_beam/yaml/yaml_mapping_test.py

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[github-actions]

📋 Review Summary

This PR cleanly resolves two bugs in Beam YAML windowing transforms: correcting the 'd' (day) duration multiplier in WindowInto._parse_duration from 12 hours (60 * 60 * 12) to 24 hours (60 * 60 * 24), and fixing _ExtractWindowingInfo so that duplicate field validation checks against field names rather than (name, type) tuples. The accompanying unit tests in yaml_transform_test.py and yaml_mapping_test.py thoroughly cover both fixes.

🔍 General Feedback

• The changes are minimal, well-scoped, and adhere to existing codebase conventions.
• Unit tests directly verify both the duration parsing helper and end-to-end YAML transform execution.

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[github-actions]

Assigning reviewers:

R: @chamikaramj for label yaml.
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