Merge bitcoin/bitcoin#30306: fuzz: Improve stability for txorphan and mini_miner harnesses

e009bf6 Don't use iterator addresses in IteratorComparator (dergoegge)

Pull request description:

  See #29018.

  Stability for `txorphan` is now >90%. `mini_miner` needs further investigation, stability still low (although slightly improved by this PR) at ~62%.

ACKs for top commit:
  marcofleon:
    Tested ACK e009bf6. Using afl++, stability for `txorphan` went from 82% to ~94% and for `mini_miner` it went from 84% to 97%. I ran them both using the corpora in qa-assets.
  glozow:
    utACK e009bf6

Tree-SHA512: 6d0a20fd7ceedca8e702d8adde5fca500d8b0187147aee8d43b4e9eb5176dcacf60180f42a7158f037d18dbb27e479b6c069a0f3c912226505cbff5aa073a415

Author: fanquake

src/node/mini_miner.h

@@ -63,7 +63,7 @@ struct IteratorComparator
     template<typename I>
     bool operator()(const I& a, const I& b) const
     {
-        return &(*a) < &(*b);
+        return a->first < b->first;
     }
 };
 

src/txorphanage.h

@@ -92,7 +92,7 @@ class TxOrphanage {
         template<typename I>
         bool operator()(const I& a, const I& b) const
         {
-            return &(*a) < &(*b);
+            return a->first < b->first;
         }
     };