Simplify DbMigrator console output.

Resolve #3658

templates/app/aspnet-core/src/MyCompanyName.MyProjectName.DbMigrator/Program.cs

@@ -2,6 +2,7 @@ using System.IO;
 using System.Threading.Tasks;
 using Microsoft.Extensions.DependencyInjection;
 using Microsoft.Extensions.Hosting;
+using Microsoft.Extensions.Logging;
 using Serilog;
 using Serilog.Events;
 
@@ -30,6 +31,7 @@ namespace MyCompanyName.MyProjectName.DbMigrator
 
         public static IHostBuilder CreateHostBuilder(string[] args) =>
             Host.CreateDefaultBuilder(args)
+                .ConfigureLogging((context, logging) => logging.ClearProviders())
                 .ConfigureServices((hostContext, services) =>
                 {
                     services.AddHostedService<DbMigratorHostedService>();