win,test: de-flake fs_event_watch_dir_short_path
win,test: de-flake fs_event_watch_dir_short_path

New versions of Windows ship with 8.3 short-names disabled.
This commit adds 8.3 detection logic in the
fs_event_watch_dir_short_path test.

PR-URL: https://github.com/libuv/libuv/pull/2103
Reviewed-By: Ben Noordhuis <59bd0a3ff43b32849b319e645d4798d8a5d1e889@bnoordhuis.nl>
Reviewed-By: Bartosz Sosnowski <aa4e0bd35c562885f21ad74b171c23cfc4370e31@janeasystems.com>
Reviewed-By: Colin Ihrig <838f779c91673db29b8572ea3f54d191d3878ae2@gmail.com>

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