server: enable ExtraBudgetForInputs to be called before full server start up

This is a pure function that just returns what's basically a static
value. There's no risk of deadlock if a caller calls into this function
before the server has fully started up.

Author: Roasbeef

server.go

@@ -1262,10 +1262,6 @@ func (s *Server) ExtraBudgetForInputs(
 	srvrLog.Tracef("ExtraBudgetForInputs called, inputs=%v",
 		lnutils.SpewLogClosure(inputs))
 
-	if err := s.waitForReady(); err != nil {
-		return lfn.Err[btcutil.Amount](err)
-	}
-
 	return s.cfg.AuxSweeper.ExtraBudgetForInputs(inputs)
 }