rabbit_db_exchange: Allow infinite timeout for serial updates in Khepri

It's unlikely that these operations will time out since the serial
number is always updated after some other transaction, for example
adding or deleting an exchange.

In the future we could consider moving the serial updates into those
transactions. In the meantime we can remove the possibility of timeouts
by giving the serial update unlimited time to finish.

(cherry picked from commit 7059582)

Author: the-mikedavis

deps/rabbit/src/rabbit_db_exchange.erl

@@ -524,17 +524,15 @@ next_serial_in_khepri(XName) ->
             UpdatePath =
                 khepri_path:combine_with_conditions(
                   Path, [#if_payload_version{version = Vsn}]),
-            case rabbit_khepri:put(UpdatePath, Serial + 1) of
+            case rabbit_khepri:put(UpdatePath, Serial + 1, #{timeout => infinity}) of
                 ok ->
                     Serial;
                 {error, {khepri, mismatching_node, _}} ->
-                    next_serial_in_khepri(XName);
-                Err ->
-                    Err
+                    next_serial_in_khepri(XName)
             end;
         _ ->
             Serial = 1,
-            ok = rabbit_khepri:put(Path, Serial + 1),
+            ok = rabbit_khepri:put(Path, Serial + 1, #{timeout => infinity}),
             Serial
     end.