Revert "Set EF DbContext pool size to 1024 (instead of default 128) (a…

…spnet#1630)"

This reverts commit ae736a9.

src/Benchmarks/Startup.cs

@@ -77,7 +77,7 @@ public void ConfigureServices(IServiceCollection services)
                     if (settings.Enlist)
                         throw new ArgumentException("Enlist=false must be specified for Npgsql");
 
-                    services.AddDbContextPool<ApplicationDbContext>(options => options.UseNpgsql(appSettings.ConnectionString), 1024);
+                    services.AddDbContextPool<ApplicationDbContext>(options => options.UseNpgsql(appSettings.ConnectionString));
 
                     if (Scenarios.Any("Raw") || Scenarios.Any("Dapper"))
                     {