Revert "types/netmap,wgengine/magicsock: propagate CapVer to magicsock.endpoint (#16244)" (#16322)

This reverts commit 6a93b17c8c.

The reverted commit added more complexity than it was worth at the
current stage. Handling delta CapVer changes requires extensive changes
to relayManager datastructures in order to also support delta updates of
relay servers.

Updates tailscale/corp#27502

Signed-off-by: Jordan Whited <jordan@tailscale.com>

wgengine/magicsock/magicsock.go

@@ -3263,10 +3263,6 @@ func (c *Conn) onNodeMutationsUpdate(update NodeMutationsUpdate) {
 			ep.mu.Lock()
 			ep.setEndpointsLocked(views.SliceOf(m.Endpoints))
 			ep.mu.Unlock()
-		case netmap.NodeMutationCap:
-			ep.mu.Lock()
-			ep.relayCapable = capVerIsRelayCapable(m.Cap)
-			ep.mu.Unlock()
 		}
 	}
 }