This partially reverts f3d2fd2.
When that patch was written, the goroutine that responds to IPN notifications
could call `StartLoginInteractive`, creating a race condition that led to
flaky integration tests. We no longer call `StartLoginInteractive` in that
goroutine, so the race is now impossible.
Moving the `WatchIPNBus` call earlier ensures the CLI gets all necessary
IPN notifications, preventing a reauth from hanging.
Updates tailscale/corp#31476
Signed-off-by: Alex Chan <alexc@tailscale.com>
c011369de2