more rack bay work, fixes and code cleanup

sbc_case_builder.json

@@ -11081,7 +11081,7 @@
             "rack_bay6_rear_conduit": "true",
             "rack_bay6_rear_fan": "true",
             "rack_bay6_rotation": "270",
-            "rack_bay6_xyz_loc": "[385, 0, 0]",
+            "rack_bay6_xyz_loc": "[383, 0, 0]",
             "rack_size": "1u",
             "rack_width": "19",
             "raise_top": "0",
@@ -11097,7 +11097,7 @@
             "sbc_information": "false",
             "sbc_model": "c4",
             "sbc_off": "false",
-            "sbc_top_standoffs": "true",
+            "sbc_top_standoffs": "false",
             "section_part": "false",
             "sidethick": "5",
             "standard_motherboard_thickness": "0",
@@ -11129,7 +11129,7 @@
             "top_standoff_support_height": "4",
             "top_standoff_support_size": "10",
             "top_standoff_type": "blind",
-            "uart_opening": "default",
+            "uart_opening": "none",
             "view": "model",
             "wallthick": "3"
         }