Another baby step toward removing slices of peers from the engine.
getStatus iterated peerSequence (a key snapshot built in Reconfig
from cfg.Peers) and then asked wgdev for each peer's stats; peers
that weren't active in wgdev silently fell out. Iterate active wgdev
peers directly via RemoveMatchingPeers(returnFalse) instead.
Updates #12542
Signed-off-by: Brad Fitzpatrick <bradfitz@tailscale.com>
Change-Id: I3abd348abc30db706db29b3a785179259e48abda
Brad Fitzpatrick
e9ae398199