testboard: less noise standard output

Use '> ' instead of '[log] ', since this is not a log file but
usually read interactively.

Signed-off-by: Gerwin Klein <gerwin.klein@proofcraft.systems>

misc/testboard/testboardpush

@@ -72,7 +72,7 @@ def main(argv):
         if args.quiet:
             return
         for line in msg.split('\n'):
-            sys.stdout.write('[log] ' + line + '\n')
+            sys.stdout.write('> ' + line + '\n')
     def debug(msg):
         if not args.debug:
             return