[wallet] Remove keypool_topup_cleanups

Unused function. Mostly reverts c25d90f125

c25d90f... was merged as part of PR 11022 but is not required.

src/wallet/wallet.cpp

@@ -3663,11 +3663,6 @@ void CWallet::MarkReserveKeysAsUsed(int64_t keypool_id)
     }
 }
 
-bool CWallet::HasUnusedKeys(int min_keys) const
-{
-    return setExternalKeyPool.size() >= min_keys && (setInternalKeyPool.size() >= min_keys || !CanSupportFeature(FEATURE_HD_SPLIT));
-}
-
 void CWallet::GetScriptForMining(std::shared_ptr<CReserveScript> &script)
 {
     std::shared_ptr<CReserveKey> rKey = std::make_shared<CReserveKey>(this);

src/wallet/wallet.h

@@ -984,8 +984,6 @@ public:
      */
     void MarkReserveKeysAsUsed(int64_t keypool_id);
     const std::map<CKeyID, int64_t>& GetAllReserveKeys() const { return m_pool_key_to_index; }
-    /** Does the wallet have at least min_keys in the keypool? */
-    bool HasUnusedKeys(int min_keys) const;
 
     std::set< std::set<CTxDestination> > GetAddressGroupings();
     std::map<CTxDestination, CAmount> GetAddressBalances();