Global Styles: Remove orphaned get_svg_filters() method

[annezazu]

Summary

Removes the unused get_svg_filters() method from WP_Theme_JSON_Gutenberg that was left behind after PR #49103 moved duotone functionality to WP_Duotone_Gutenberg.

What Changed

• Removed the orphaned get_svg_filters() method (34 lines) from lib/class-wp-theme-json-gutenberg.php

Why

After PR #49103 consolidated duotone generation logic in WP_Duotone_Gutenberg, this method became orphaned:

• ❌ No callers exist in the codebase
• ❌ Calls a non-existent function (wp_get_duotone_filter_svg)
• ✅ Functionality fully replaced by WP_Duotone_Gutenberg::get_svg_definitions()

Testing

• Verified no callers exist for this method
• Verified PHP syntax is valid after removal
• No tests reference this method

Closes #49213

🤖 Generated with Claude Code

[github-actions]

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[github-actions]

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Co-authored-by: annezazu <annezazu@git.wordpress.org>
Co-authored-by: Mamaduka <mamaduka@git.wordpress.org>
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[github-actions]

Flaky tests detected in c146764.
Some tests passed with failed attempts. The failures may not be related to this commit but are still reported for visibility. See the documentation for more information.

🔍 Workflow run URL: https://github.com/WordPress/gutenberg/actions/runs/20291666673
📝 Reported issues:

• [Flaky Test] should open and edit templates correctly when active_templates experiment is disabled #73743 in /test/e2e/specs/site-editor/template-id-format.spec.js

[Mamaduka]

This class is synced with the core. Unfortunately, we can't remove public methods because it would break backward compatibility.

It's probably better to deprecate it and noop it. I'm sure there will be examples in the core for similar cases.

[annezazu]

Sweet. I'll poke around and see if I can make that happen. Closing this out for now.