Util: Consolidate linux service detection code

apps/routerconsole/java/src/net/i2p/router/web/ConfigServiceHandler.java

@@ -201,7 +201,7 @@ public class ConfigServiceHandler extends FormHandler {
      */
     public boolean shouldShowSystray() {
         return !
-            (RouterConsoleRunner.DAEMON_USER.equals(System.getProperty("user.name")) ||
+            (SystemVersion.isLinuxService() ||
              (SystemVersion.isWindows() && _context.hasWrapper() && WrapperManager.isLaunchedAsService()) ||
              // headless=true is forced in i2prouter script to prevent useless dock icon;
              // must fix this first