Increase the txn lock timeout in stress test (#7823)

Summary:
We recently encounter two cases of txn lock timeout in stress test. It might be caused due to latencies of resource scheduling in the internal infrastructure. Hopefully increasing the timeout can make the related tests less flaky.

Pull Request resolved: https://github.com/facebook/rocksdb/pull/7823

Test Plan: watch internal stress test to pass.

Reviewed By: siying

Differential Revision: D25739233

Pulled By: cheng-chang

fbshipit-source-id: 84a5a8ae820db24dacd0cfc05928b26505fab89d

db_stress_tool/db_stress_test_base.cc

@@ -472,7 +472,7 @@ Status StressTest::NewTxn(WriteOptions& write_opts, Transaction** txn) {
   }
   static std::atomic<uint64_t> txn_id = {0};
   TransactionOptions txn_options;
-  txn_options.lock_timeout = 60000;  // 1min
+  txn_options.lock_timeout = 600000;  // 10 min
   txn_options.deadlock_detect = true;
   *txn = txn_db_->BeginTransaction(write_opts, txn_options);
   auto istr = std::to_string(txn_id.fetch_add(1));