orderfile: make --new-commit-flow the default

The bot has been using --new-commit-flow for a while now (see
http://crbug.com/908406). Make this the default to later remove and make
it less confusingly not new.

Bug: 1028600
Change-Id: Iebbb7f5362083155b7c53bdb2da4624b713236bc
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1936494
Auto-Submit: Egor Pasko <pasko@chromium.org>
Reviewed-by: John Budorick <jbudorick@chromium.org>
Commit-Queue: John Budorick <jbudorick@chromium.org>
Commit-Queue: Egor Pasko <pasko@chromium.org>
Cr-Commit-Position: refs/heads/master@{#719163}

tools/cygprofile/orderfile_generator_backend.py

@@ -1195,7 +1195,7 @@ def CreateArgumentParser():
   parser.add_argument('--commit-hashes', action='store_true',
                       help=('Commit any orderfile hash files in the current '
                             'checkout; performs no other action'))
-  parser.add_argument('--new-commit-flow', action='store_true',
+  parser.add_argument('--new-commit-flow', action='store_true', default=True,
                       help='Use the new two-step commit flow.')
   parser.add_argument('--use-call-graph', action='store_true', default=False,
                       help='Use call graph instrumentation.')