rpc: allow getting pruned blocks from gettransactions

and get them pruned in find_and_save_rings, since it does not need
the pruned data in the first place.

Also set decode_to_json to false where missing, we don't need this
either.

src/wallet/wallet2.cpp

@@ -5610,7 +5610,24 @@ bool wallet2::find_and_save_rings(bool force)
     txs_hashes.push_back(txid);
   }
 
-  MDEBUG("Found " << std::to_string(txs_hashes.size()) << " transactions");
+  MDEBUG("Found " << std::to_string(req.txs_hashes.size()) << " transactions");
+
+  // get those transactions from the daemon
+  req.decode_as_json = false;
+  req.prune = true;
+  bool r;
+  {
+    const boost::lock_guard<boost::mutex> lock{m_daemon_rpc_mutex};
+    r = epee::net_utils::invoke_http_json("/gettransactions", req, res, m_http_client, rpc_timeout);
+  }
+  THROW_WALLET_EXCEPTION_IF(!r, error::no_connection_to_daemon, "gettransactions");
+  THROW_WALLET_EXCEPTION_IF(res.status == CORE_RPC_STATUS_BUSY, error::daemon_busy, "gettransactions");
+  THROW_WALLET_EXCEPTION_IF(res.status != CORE_RPC_STATUS_OK, error::wallet_internal_error, "gettransactions");
+  THROW_WALLET_EXCEPTION_IF(res.txs.size() != req.txs_hashes.size(), error::wallet_internal_error,
+    "daemon returned wrong response for gettransactions, wrong txs count = " +
+    std::to_string(res.txs.size()) + ", expected " + std::to_string(req.txs_hashes.size()));
+
+  MDEBUG("Scanning " << res.txs.size() << " transactions");
 
   crypto::chacha_key key;
   generate_chacha_key_from_secret_keys(key);