Fix nested DISTINCT projection classification #494

Job	Run time
Build extension binaries / Generate matrix	7s
Code Quality Check / Format Check	2m 40s
Code Quality Check / Tidy Check	38m 19s
Build extension binaries / Linux (linux_arm64, ubuntu-24.04-arm, arm64-linux-release, arm64-linux-release, false, false)	7m 44s
Build extension binaries / Linux (linux_amd64, ubuntu-24.04, x64-linux-release, x64-linux-release, true, false)	12m 7s
Build extension binaries / Windows (windows_amd64_mingw, windows-latest, x64-mingw-static, x64-mingw-static, true, false)	17m 55s
Build extension binaries / MacOS (osx_arm64, arm64, arm64-osx-release, arm64-osx-release, true, false)	7m 51s
Build extension binaries / DuckDB-Wasm (wasm_eh, wasm32-emscripten, x64-linux, false, false)	9m 59s
Build extension binaries / DuckDB-Wasm (wasm_mvp, wasm32-emscripten, x64-linux, true, false)	11m 51s
Build extension binaries / DuckDB-Wasm (wasm_threads, wasm32-emscripten, x64-linux, false, false)	13m 46s
Build extension binaries / Windows (windows_amd64, windows-latest, x64-windows-static-release, x64-windows-static-release, t...	12m 51s
Build extension binaries / MacOS (osx_amd64, x86_64, x64-osx-release, arm64-osx-release, false, false)	5m 56s
	2h 21m 6s

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