Fix disabled block allowlist handling

[dknauss]

Description of the Change

Fixes an edge case in the disabled-comments block allowlist filter.

When another allowed_block_types_all filter has already returned false, WordPress interprets that as "no blocks allowed." The current comments filter replaces that value with a full registered-block allowlist minus comment blocks, which unintentionally re-enables blocks that an earlier filter disabled.

This change preserves false and only builds a filtered block list when blocks are otherwise allowed.

Benefits

• Preserves WordPress/core filter semantics.
• Avoids overriding stricter block restrictions from another plugin, theme, or project filter.
• Keeps the existing comment-block removal behavior for normal true or array allowlists.

Possible Drawbacks

None expected. This only changes behavior when a previous filter has already disabled all blocks.

Verification Process

• php -l includes/classes/Comments/Comments.php
• composer run lint
• git diff --check

Changelog Entry

Fixed - Preserve disabled block allowlists when removing comment blocks.

Checklist:

• My code follows the code style of this project.
• All new and existing tests pass. (No automated test suite exists in this repo; CI runs lint only.)

A note on tests

This change has unit-testable logic, but the plugin currently ships no test harness (no PHPUnit or e2e setup; CI runs lint only), so there's nothing here to add coverage to. I'm happy to contribute a minimal test setup plus coverage for this in a separate PR if that's welcome.

AI assistance was used in drafting and reviewing this change; final authorship and verification are mine.