CSHARP-2377: Enable unit tests that are not being run (#1339)

Author: sanych-sun

tests/MongoDB.Driver.Core.Tests/MongoDB.Driver.Core.Tests.csproj

@@ -18,7 +18,6 @@
   <PropertyGroup>
     <NoWarn>
       1701;1702; <!--https://github.com/dotnet/roslyn/issues/19640-->
-      xUnit1000; <!--A class containing test methods is not public (https://xunit.github.io/xunit.analyzers/rules/xUnit1000.html)-->
       xUnit1010; <!--The value is not convertible to the method parameter type (https://xunit.github.io/xunit.analyzers/rules/xUnit1010.html)-->
       xUnit1013; <!--Public method should be marked as test (https://xunit.github.io/xunit.analyzers/rules/xUnit1013.html)-->
       xUnit1014; <!--MemberData should use nameof operator for member name (https://xunit.github.io/xunit.analyzers/rules/xUnit1014.html)-->