ra_server_proc: Defer a call to determine_leader/2 to where it's ne…

…eded

[Why]
If the query has a condition, the result of the call to
`determine_leader/2` is not used. Furthermore, it is called again by
another function further down the line.

src/ra_server_proc.erl

@@ -1188,9 +1188,9 @@ perform_or_delay_local_query(
     %% If the condition is set to `{applied, {Index, Term}}', the query is
     %% added to a list of pending queries. It will be evaluated once that
     %% index is applied locally.
-    Leader = determine_leader(RaftState, State),
     case maps:get(condition, Options, undefined) of
         undefined ->
+            Leader = determine_leader(RaftState, State),
             Reply = perform_local_query(QueryFun, Leader, ServerState, Conf),
             {keep_state, State, [{reply, From, Reply}]};
         Condition ->