Reverted `$ custom-control-indicator-border-color` to the original color.

src/client/styles/scss/_override-bootstrap-variables.scss

@@ -64,7 +64,7 @@ $input-border-radius-lg: $border-radius;
 
 $input-placeholder-color: $gray-500;
 
-$custom-control-indicator-border-color: $border-color;
+$custom-control-indicator-border-color: $gray-400;
 $custom-control-label-disabled-color: $gray-500;
 $custom-select-disabled-color: $gray-500;
 $custom-range-thumb-disabled-bg: $gray-400;