refactor: Remove unimportant labels

Removed "label" properties which no longer have any function.

Labels are still used as layer names and as identifiers for sending
behaviors between sides of a split keyboard, so those have been left
alone for now.

app/boards/shields/splitreus62/splitreus62.dtsi

@@ -34,7 +34,6 @@ RC(4,0) RC(4,1) RC(4,2) RC(4,3) RC(4,4) RC(4,5)                 RC(4,6) RC(4,7)
 
     kscan0: kscan {
         compatible = "zmk,kscan-gpio-matrix";
-        label = "KSCAN";
 
         diode-direction = "row2col";
         row-gpios