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

wgengine/magicsock/magicsock.go

@@ -3160,7 +3160,6 @@ func (c *Conn) goroutinesRunningLocked() bool {
 	if c.activeDerp != nil {
 		select {
 		case <-c.derpStarted:
-			break
 		default:
 			return true
 		}