cmd/cli: ensure DNS goroutines terminated before self-uninstall

Otherwise, these goroutines could mess up with what resetDNS function
do, reverting DHCP DNS settings to ctrld listeners.

cmd/cli/dns_proxy.go

@@ -863,7 +863,7 @@ func (p *prog) doSelfUninstall(answer *dns.Msg) {
 		p.checkingSelfUninstall = true
 		_, err := controld.FetchResolverConfig(cdUID, rootCmd.Version, cdDev)
 		logger.Debug().Msg("maximum number of refused queries reached, checking device status")
-		selfUninstall(err, p, logger)
+		selfUninstallCheck(err, p, logger)
 
 		if err != nil {
 			logger.Warn().Err(err).Msg("could not fetch resolver config")