depot_tools: add a `--dry-run` alias to `--cq-dry-run`

It is easier to remember.

Bug: none
Change-Id: I075fe57521c9743901f51bd1ed3476145553dc48
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/tools/depot_tools/+/5010037
Commit-Queue: Aravind Vasudevan <aravindvasudev@google.com>
Auto-Submit: Thiago Perrotta <tperrotta@chromium.org>
Reviewed-by: Aravind Vasudevan <aravindvasudev@google.com>

git_cl.py

@@ -4923,8 +4923,10 @@ def CMDupload(parser, args):
                       help='tell the CQ to commit this patchset; '
                       'implies --send-mail')
     parser.add_option('-d',
+                      '--dry-run',
                       '--cq-dry-run',
                       action='store_true',
+                      dest='cq_dry_run',
                       default=False,
                       help='Send the patchset to do a CQ dry run right after '
                       'upload.')