is_arial compared the family and style without regard to case but
stripped the MT suffix case-sensitively, so arialmt and Arial-Boldmt
weren't read in Arial's glyph order (CodeRabbit review on #6210). The
suffix is now stripped in any case, slicing only at a char boundary.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>