Merge pull request #15621 from tamasvajk/buildless/cleanup

C#: Code quality improvements (fixed log message, removed unused interface)

Author: tamasvajk

csharp/extractor/Semmle.Extraction.CSharp.DependencyFetching/DependencyManager.cs

@@ -417,7 +417,7 @@ private void LogAllUnusedPackages(DependencyContainer dependencies)
             var allPackageDirectories = GetAllPackageDirectories();
 
             logger.LogInfo($"Restored {allPackageDirectories.Count} packages");
-            logger.LogInfo($"Found {dependencies.Packages.Count} packages in project.asset.json files");
+            logger.LogInfo($"Found {dependencies.Packages.Count} packages in project.assets.json files");
 
             allPackageDirectories
                 .Where(package => !dependencies.Packages.Contains(package))