Remove legacy bitcoind txindex param from apitest harness

It was put there thinking it would be needed by the test harness and suites,
which work fine without it, and it must be removed before API test harness
can run against bitcoin-core v23.

See bitcoin/bitcoin#22626 (comment)

apitest/src/main/java/bisq/apitest/linux/BitcoinDaemon.java

@@ -52,7 +52,6 @@ public void start() throws InterruptedException, IOException {
                 + " -daemon"
                 + " -regtest=1"
                 + " -server=1"
-                + " -txindex=1"
                 + " -peerbloomfilters=1"
                 + " -debug=net"
                 + " -fallbackfee=0.0002"