Wipe NSIS install preferences when uninstalling

The user language and start menu folder name were saved, which goes
against recommendations in the NSIS documentation.

The installation directory was also saved, which might make sense,
but prevents us from dropping the "alpha" label.

Reviewed-At: https://gitea.wildfiregames.com/0ad/0ad/pulls/8476
Fixes: #7594

source/tools/dist/0ad.nsi

@@ -29,9 +29,6 @@
   InstallDir "$LOCALAPPDATA\0 A.D. Empires Ascendant"
   ; NOTE: "0 A.D." doesn't work as a folder/start menu folder name, the final dot gets stripped.
 
-  ;Get installation folder from registry if available
-  InstallDirRegKey HKCU "Software\0 A.D." ""
-
   RequestExecutionLevel user
 
 ;--------------------------------
@@ -234,6 +231,10 @@ uninst:
 
 done:
 
+  ;In alpha versions, the uninstaller preserved the registry key containing user install preferences
+  DeleteRegKey HKCU "Software\0 A.D."
+  ClearErrors
+
 FunctionEnd
 
 Function CreateDesktopLink
@@ -290,7 +291,7 @@ Section "Uninstall"
   RMDir "$SMPROGRAMS\$StartMenuFolder"
 
   DeleteRegKey SHCTX "Software\Microsoft\Windows\CurrentVersion\Uninstall\0 A.D."
-  DeleteRegKey /ifempty SHCTX "Software\0 A.D."
+  DeleteRegKey SHCTX "Software\0 A.D."
 
   ;Unregister .pyromod file association
   ${unregisterExtension} ".pyromod" "Pyrogenesis mod"