scripted-diff: Replace MilliSleep with UninterruptibleSleep

This is safe because MilliSleep is never executed in a boost::thread,
the only type of thread that is interruptible.

* The RPC server uses std::thread
* The wallet is either executed in an RPC thread or the main thread
* bitcoin-cli, benchmarks and tests are only one thread (the main thread)

-BEGIN VERIFY SCRIPT-
sed -i --regexp-extended -e 's/MilliSleep\((\S+)\);/UninterruptibleSleep(std::chrono::milliseconds{\1});/g' $(git grep -l MilliSleep)
-END VERIFY SCRIPT-

src/test/txindex_tests.cpp

@@ -34,7 +34,7 @@ BOOST_FIXTURE_TEST_CASE(txindex_initial_sync, TestChain100Setup)
     int64_t time_start = GetTimeMillis();
     while (!txindex.BlockUntilSyncedToCurrentChain()) {
         BOOST_REQUIRE(time_start + timeout_ms > GetTimeMillis());
-        MilliSleep(100);
+        UninterruptibleSleep(std::chrono::milliseconds{100});
     }
 
     // Check that txindex excludes genesis block transactions.