Migrate build target markers to keyboard.json - S (#23532)

keyboards/sixkeyboard/keyboard.json

@@ -9,6 +9,12 @@
     "device_version": "0.0.1",
     "force_nkro": true
   },
+  "features": {
+    "bootmagic": false,
+    "extrakey": false,
+    "mousekey": false,
+    "nkro": false
+  },
   "processor": "atmega16u2",
   "bootloader": "atmel-dfu",
   "community_layouts": ["ortho_2x3"],

keyboards/sixkeyboard/rules.mk

@@ -1,14 +1,3 @@
-# Build Options
-#   change yes to no to disable
-#
-BOOTMAGIC_ENABLE = no       # Enable Bootmagic Lite
-MOUSEKEY_ENABLE = no		# Mouse keys
-EXTRAKEY_ENABLE = no		# Audio control and System control
-CONSOLE_ENABLE = no		# Console for debug
-COMMAND_ENABLE = no		# Commands for debug and configuration
-NKRO_ENABLE = no            # Enable N-Key Rollover
-BACKLIGHT_ENABLE = no	# Enable keyboard backlight functionality
-AUDIO_ENABLE = no
 CUSTOM_MATRIX = yes
 
 SRC += matrix.c