refactor(adminui): explicit discard on fire-and-forget audit + Untrust not-found test (review)

tests/Server/ZB.MOM.WW.OtOpcUa.AdminUI.Tests/Certificates/CertificateStoreManagerTests.cs

@@ -288,4 +288,19 @@ public sealed class CertificateStoreManagerTests : IDisposable
         evt.SourceNode.ShouldBe(absent);
         evt.Actor.ShouldBe("bob");
     }
+
+    [Fact]
+    public void Untrust_not_found_writes_one_failure_audit_event()
+    {
+        var absent = new string('0', 40);
+
+        var result = _sut.Untrust(absent, "erin");
+
+        result.Success.ShouldBeFalse();
+        var evt = _audit.Events.ShouldHaveSingleItem();
+        evt.Action.ShouldBe("Untrust");
+        evt.Outcome.ShouldBe(ZB.MOM.WW.Audit.AuditOutcome.Failure);
+        evt.SourceNode.ShouldBe(absent);
+        evt.Actor.ShouldBe("erin");
+    }
 }