ci: add more lints (#7909)

This is a follow-up to #7905 that adds two more linters and fixes the corresponding findings. As per the previous PR, this only flags things that are "obviously" wrong, and fixes the issues found.

Signed-off-by: Andrew Dunham <andrew@du.nham.ca>
Change-Id: I8739bdb7bc4f75666a7385a7a26d56ec13741b7c

cmd/tailscale/cli/netcheck.go

@@ -97,7 +97,6 @@ func printReport(dm *tailcfg.DERPMap, report *netcheck.Report) error {
 	var err error
 	switch netcheckArgs.format {
 	case "":
-		break
 	case "json":
 		j, err = json.MarshalIndent(report, "", "\t")
 	case "json-line":