MySQL: Fixes NRE on Catalog extraction (part 2)

Author: alex-kulakov

Orm/Xtensive.Orm.MySql/Sql.Drivers.MySql/v5_0/Extractor.cs

@@ -120,7 +120,7 @@ public override Catalog ExtractCatalog(string catalogName) =>
 
     /// <inheritdoc/>
     public override Task<Catalog> ExtractCatalogAsync(string catalogName, CancellationToken token = default) =>
-      ExtractSchemesAsync(catalogName, Array.Empty<string>(), token);
+      ExtractSchemesAsync(catalogName, new[] { Driver.CoreServerInfo.DefaultSchemaName }, token);
 
     /// <inheritdoc/>
     public override Catalog ExtractSchemes(string catalogName, string[] schemaNames)