Issue #3563784: Improve debug output formatting

Boris Doesborgrequested to merge
issue/migrate_devel-3563784:3563784-improve-output into 3.x

Remove line numbers from debug output, remove dollar signs from variable headers, and add newline before output to prevent layout issues with Drush progress bars.

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Co-Authored-By: Claude Opus 4.5 noreply@anthropic.com

Closes #3563784

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