Remove incorrect use of split.main (#24158)

keyboards/aidansmithdotdev/sango/keyboard.json

@@ -120,7 +120,6 @@
             "matrix": [4, 7]
         },
         "enabled": true,
-        "main": "matrix_grid",
         "matrix_pins": {
             "right": {
                 "cols": ["GP7", "GP8", "GP9", "GP11", "GP12", "GP13", "GP14", "GP15"],

keyboards/takashicompany/heavy_left/keyboard.json

@@ -45,8 +45,7 @@
     "diode_direction": "COL2ROW",
     "split": {
         "enabled": true,
-        "soft_serial_pin": "D2",
-        "main": "eeprom"
+        "soft_serial_pin": "D2"
     },
     "development_board": "promicro",
     "layouts": {