chainntnfs: modify GetTestTxidAndScript to generate new P2PKH scripts

In this commit, we modify GetTestTxidAndScript to generate new P2PKH
scripts. This is needed to properly test confirmations and spends of
unique scripts on-chain within the set of interface-level test cases.

chainntnfs/bitcoindnotify/bitcoind_test.go

@@ -197,7 +197,7 @@ func TestHistoricalConfDetailsTxIndex(t *testing.T) {
 // historical confirmation details using the set of fallback methods when the
 // backend node's txindex is disabled.
 func TestHistoricalConfDetailsNoTxIndex(t *testing.T) {
-	miner, tearDown := chainntnfs.NewMiner(t, nil, true, 400)
+	miner, tearDown := chainntnfs.NewMiner(t, nil, true, 25)
 	defer tearDown()
 
 	bitcoindConn, cleanUp := chainntnfs.NewBitcoindBackend(