Currently, clientupdate.NewUpdater().Update() is called directly inside tailscaled, which fatals. There is also a failure that doesn't return, causing a panic.
This fix allows us to use the same approach as startAutoUpdate, which is to find tailscale.exe and run tailscale.exe --update, though since it's calling the updater library directly, we get progress messages.
Fixes tailscale/corp#40430s
Signed-off-by: kari-ts <kari@tailscale.com>
8dda62cc24