Remove misleading comment

- the foreground informaton **is** not updated by this function
- not all callers call updateForegroundProcessInfo() afterwards
- other functions have a call to updateForegroundProcessInfo()
  inside, so the whole thing is moot
- this commit message is 5x as long as the comment it removes

src/session/Session.cpp

@@ -1620,8 +1620,6 @@ int Session::foregroundProcessId()
 
 bool Session::isForegroundProcessActive()
 {
-    // foreground process info is always updated after this
-
     // This check is wrong when Konsole is started with '-e cmd'
     // as there will only be one process.
     // See BKO 134581 for no popup when closing session