The previous LocalBackend & CLI 'up' changes improved some stuff, but
might've been too aggressive in some edge cases.
This simplifies the authURL vs authURLSticky distinction and removes
the interact field, which seemed to just just be about duplicate URL
suppression in IPN bus, back from when the IPN bus was a single client
at a time. This moves that suppression to a different spot.
Fixes#12119
Updates #12028
Updates #12042
Change-Id: I1f8800b1e82ccc1c8a0d7abba559e7404ddf41e4
Signed-off-by: Brad Fitzpatrick <bradfitz@tailscale.com>
8aa5c3534d