dnsdist: Remove a racy test in the AsynchronousHolder unit tests

We are adding an expired event so the worker thread of the
AsynchronousHolder can pick it up immediately, even before we come
back from the call to push(), which leads to a racy test.
This was observed on GitHub Actions when running with TSAN:
```
FAIL: testrunner
================

Running 170 test cases...
test-dnsdistasync.cc(156): error: in "test_dnsdistasync/test_AddingExpiredEvent": check !holder->empty() has failed

*** 1 failure is detected in the test module "unit"
FAIL testrunner (exit status: 201)
```

diff --git a/pdns/dnsdistdist/test-dnsdistasync.cc b/pdns/dnsdistdist/test-dnsdistasync.cc
index 802ba4021d116f43429593e725c8af8d48c4d0bd..b1fbebca053b8b483e523f875ceebfa51614747b 100644 (file)
--- a/pdns/dnsdistdist/test-dnsdistasync.cc
+++ b/pdns/dnsdistdist/test-dnsdistasync.cc
@@ -153,7 +153,6 @@ BOOST_AUTO_TEST_CASE(test_AddingExpiredEvent)
     sender = query->d_sender;
     BOOST_REQUIRE(sender != nullptr);
     holder->push(asyncID, queryID, ttd, std::move(query));
-    BOOST_CHECK(!holder->empty());
   }
 
   // sleep for 20 ms