fix(ooniprobe): send batch output to stdout (#261)

Rationale explained in detail in a documentation comment.

Reference issue: https://github.com/ooni/probe/issues/1384.

cmd/ooniprobe/internal/log/handlers/cli/cli.go

@@ -14,7 +14,7 @@ import (
 	"github.com/ooni/probe-cli/v3/cmd/ooniprobe/internal/utils"
 )
 
-// Default handler outputting to stderr.
+// Default handler outputting to stdout.
 var Default = New(os.Stdout)
 
 // start time.