WSL appends every Windows PATH entry (Desktop app, git, node dirs) to the
Linux PATH as /mnt/... ahead of the interop defaults.
_build_wsl_interop_paths() scraped all of them into the generated systemd
unit's Environment=PATH, so the gateway opened a 9p (Plan 9 interop)
connection to each at start — enough to exhaust the 9p server connection
limit and wedge gateway startup (#73163). Interop only needs
powershell.exe/cmd.exe/explorer.exe/wsl.exe: the which()-resolved tool
dirs plus the hardcoded System32 family (both kept, existence-gated and
deduped) already cover every interop call, so drop the PATH scrape.
Co-authored-by: ygd58 <buraysandro9@gmail.com>
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