LibGfx: Do not draw U+FFFD for unknown glyphs

The Replacement Character (U+FFFD) is most commonly used to signal a
text encoding error, i.e. when a stream of bytes couldn't be converted
to a sequence of code points. For glyphs that don't exist in a
particular font, our rendering logic already does the right thing by
drawing empty boxes (`.notdef`); let's not forcibly turn these into
U+FFFD during rendering.

Userland/Libraries/LibGfx/TextLayout.cpp

@@ -48,19 +48,9 @@ DrawGlyphOrEmoji prepare_draw_glyph_or_emoji(FloatPoint point, Utf8CodePointIter
         };
     }
 
-    // If that failed, but we have a text glyph fallback, draw that.
-    if (font_contains_glyph) {
-        return DrawGlyph {
-            .position = point,
-            .code_point = code_point,
-        };
-    }
-
-    // No suitable glyph found, draw a replacement character.
-    dbgln_if(EMOJI_DEBUG, "Failed to find a glyph or emoji for code_point {}", code_point);
     return DrawGlyph {
         .position = point,
-        .code_point = 0xFFFD,
+        .code_point = code_point,
     };
 }