test(historian): pass TestContext.Current.CancellationToken in the batched alarm-writer test (lmxopcua#746)

The batched-alarm-history test came from the lane-H2 branch, which predates
the xUnit1051 sweep on master (lmxopcua#725). Two no-token calls broke the
Release build under TreatWarningsAsErrors after the rebase.

Claude-Session: https://claude.ai/code/session_01GT67AEHd2Acv1YPwGfXEoV

tests/Drivers/ZB.MOM.WW.OtOpcUa.Driver.Historian.SqlServer.IntegrationTests/AlarmWriterTests.cs

@@ -101,10 +101,10 @@ public sealed class AlarmWriterTests(SqlHistorianFixture fx)
         r.Count.ShouldBe(401);
         r.ShouldAllBe(o => o == HistorianWriteOutcome.Ack);
         await using var c = new SqlConnection(fx.ConnectionString);
-        await c.OpenAsync();
+        await c.OpenAsync(TestContext.Current.CancellationToken);
         await using var cmd = c.CreateCommand();
         cmd.CommandText = $"SELECT COUNT(*) FROM [{s}].Event";
-        Convert.ToInt32(await cmd.ExecuteScalarAsync()).ShouldBe(400);
+        Convert.ToInt32(await cmd.ExecuteScalarAsync(TestContext.Current.CancellationToken)).ShouldBe(400);
     }
 
     [Fact]