wallet2: start using new fee priorities at v5, not 14 days laer

Waiting would mean the fee used is 1x base, but the base will
have suddenly dropped

src/wallet/wallet2.cpp

@@ -3379,7 +3379,7 @@ uint64_t wallet2::get_per_kb_fee()
 int wallet2::get_fee_algorithm()
 {
   // changes at v3 and v5
-  if (use_fork_rules(5, -720 * 14))
+  if (use_fork_rules(5, 0))
     return 2;
   if (use_fork_rules(3, -720 * 14))
    return 1;