Fix carpet mocks

Author: rreusser

test/image/baselines/airfoil.png

@@ -219,15 +219,15 @@
         "xref": "x",
         "yref": "y",
         "showarrow": false,
-        "x": 0,
+        "x": 0.5,
         "y": 2.3,
         "text": "coarse/smooth grid + cheater"
       },
       {
         "xref": "x",
         "yref": "y2",
         "showarrow": false,
-        "x": 0,
+        "x": 0.5,
         "y": 2.3,
         "text": "fine/unsmoothed grid + cheater"
       },