Use MTP for importmulti "now" timestamps

qa/rpc-tests/importmulti.py

@@ -139,7 +139,7 @@ class ImportMultiTest (BitcoinTestFramework):
         # Address + Private key + !watchonly
         print("Should import an address with private key")
         address = self.nodes[0].validateaddress(self.nodes[0].getnewaddress())
-        timestamp = self.nodes[1].getblock(self.nodes[1].getbestblockhash())['time']
+        timestamp = self.nodes[1].getblock(self.nodes[1].getbestblockhash())['mediantime']
         result = self.nodes[1].importmulti([{
             "scriptPubKey": {
                 "address": address['address']

src/wallet/rpcdump.cpp

@@ -1034,7 +1034,7 @@ UniValue importmulti(const JSONRPCRequest& mainRequest)
     EnsureWalletIsUnlocked();
 
     // Verify all timestamps are present before importing any keys.
-    const int64_t now = chainActive.Tip() ? chainActive.Tip()->GetBlockTime() : 0;
+    const int64_t now = chainActive.Tip() ? chainActive.Tip()->GetMedianTimePast() : 0;
     for (const UniValue& data : requests.getValues()) {
         GetImportTimestamp(data, now);
     }