Reland "scripts: pushimage: convert to common --dry-run options"

This is a reland of commit 639be6142bfea54997077f3e415ad766a8f51347

Updated a few more call sites to use dryrun instead of dry_run as kwarg.

Original change's description:
> scripts: pushimage: convert to common --dry-run options
>
> BUG=None
> TEST=CQ passes
>
> Change-Id: Ie402bce0bcd558e39174fd6e50f3e1e82375b5fa
> Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/chromite/+/4219576
> Reviewed-by: Alex Klein <saklein@chromium.org>
> Tested-by: Mike Frysinger <vapier@chromium.org>
> Commit-Queue: Mike Frysinger <vapier@chromium.org>

BUG=None
TEST=CQ passes

Change-Id: Ibf181598be93c33b0a41b97649ae85e5540d6e34
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/chromite/+/4235199
Reviewed-by: Alex Klein <saklein@chromium.org>
Auto-Submit: Mike Frysinger <vapier@chromium.org>
Tested-by: Mike Frysinger <vapier@chromium.org>
Commit-Queue: Alex Klein <saklein@chromium.org>
diff --git a/api/controller/image_unittest.py b/api/controller/image_unittest.py
index c49498d..efe3bff 100644
--- a/api/controller/image_unittest.py
+++ b/api/controller/image_unittest.py
@@ -742,7 +742,7 @@
         MockPushImage.assert_called_with(
             request.gs_image_dir,
             request.sysroot.build_target.name,
-            dry_run=request.dryrun,
+            dryrun=request.dryrun,
             sign_types=["recovery"],
             dest_bucket=request.dest_bucket,
             force_channels=["dev", "canary"],