Protect logger targets (#13529)

Logger targets were not race protected against concurrent updates from for example `HTTPConsoleLoggerSys`.

Restrict direct access to targets and make slices immutable so a returned slice can be processed safely without locks.

internal/logger/logger.go

@@ -379,7 +379,7 @@ func logIf(ctx context.Context, err error, errKind ...interface{}) {
 	}
 
 	// Iterate over all logger targets to send the log entry
-	for _, t := range Targets {
+	for _, t := range Targets() {
 		t.Send(entry, entry.LogKind)
 	}
 }