Remove obsolete patches folder

The patches for libecl, ert and qwt were applied manually and are no
longer referenced by the build system. Also remove the corresponding
entry from the repository map documentation.

docs/agents/repo-map.md

@@ -35,7 +35,6 @@ ResInsight/
 │   └── class-diagrams/     # PlantUML class diagrams
 ├── scripts/                # Build and utility scripts
 ├── tooling/                # Development tools
-├── patches/                # Patches for dependencies
 ├── CMakeLists.txt         # Main CMake configuration
 ├── CMakePresets.json      # CMake build presets
 ├── ResInsightVersion.cmake # Version information