Add comprehensive Teradata connector pushdown functionality documentation

[dv255037]

Description

Added detailed documentation for Teradata connector pushdown capabilities including:

• Join pushdown with cost-based optimization
• Limit and Top N pushdown
• Projection and predicate pushdown
• Aggregate pushdown for numeric and string data types

This documentation covers:

• Configuration properties for join pushdown (join-pushdown.enabled, join-pushdown.strategy)
• Supported operators and functions for predicate pushdown
• Aggregate function support by data type
• Performance optimization benefits and limitations

What's included?

• One
• Two
• Three

General Tests for Every PR

Please make sure your PR adheres to the following requirements:

• npm run start still works.
• npm run build still works.
• Code adheres to project style guidelines (e.g., linting, formatting).
• Any new dependencies have been added to the appropriate files.
• The changes do not introduce new issues or regressions.

Screenshots or Visual Updates (if applicable)

[github-actions]

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2025-09-24 08:41 UTC

[sc250072]

Looks Good