Fix potential CONFIG SET bind test failure. (#8875)

Use an invalid IP address to trigger CONFIG SET bind failure, instead of DNS which is not guaranteed to always fail.

tests/unit/networking.tcl

@@ -25,7 +25,7 @@ test {CONFIG SET port number} {
 test {CONFIG SET bind address} {
     start_server {} {
         # non-valid address
-        catch {r CONFIG SET bind "some.wrong.bind.address"} e
+        catch {r CONFIG SET bind "999.999.999.999"} e
         assert_match {*Failed to bind to specified addresses*} $e
 
         # make sure server still bound to the previous address
@@ -33,4 +33,4 @@ test {CONFIG SET bind address} {
         $rd PING
         $rd close
     }
-}
+}