[installer] Ignore startmenu shortcut on update (#19618)

installer/PowerToysSetup/Product.wxs

@@ -599,6 +599,7 @@
 
     <DirectoryRef Id="ApplicationProgramsFolder">
       <Component Id="PowerToysStartMenuShortcut" >
+        <Condition>NOT PREVIOUSVERSIONSINSTALLED</Condition>
         <Shortcut Id="ApplicationStartMenuShortcut"
         Name="PowerToys (Preview)"
         Description="PowerToys - Windows system utilities to maximize productivity"