init: don't suggest --no-use-superproject on failure

When the superproject can't be fetched, repo init warns and tells users
to re-run repo init with --no-use-superproject. That choice is saved in
the checkout config (repo.superproject), so following it disables the
superproject for that checkout until it is re-inited, even though these
failures are often transient.

Drop the recommendation and keep the rest of the warning.

This is the repo init counterpart of reverting
https://gerrit-review.googlesource.com/c/git-repo/+/305622 for repo sync
(https://gerrit-review.googlesource.com/c/git-repo/+/634804).

Bug: 565845573
Change-Id: I91a6e682ef1d1c6dee07bc7969de88a681e1d239
Reviewed-on: https://gerrit-review.googlesource.com/c/git-repo/+/634784
Tested-by: Ram Peri <ramperi@google.com>
Reviewed-by: Sam Saccone <samccone@google.com>
Reviewed-by: Arif Kasim <arifkasim@google.com>
Commit-Queue: Ram Peri <ramperi@google.com>

project.py

@@ -6187,9 +6187,8 @@ class ManifestProject(MetaProject):
                 logger.warning(
                     "warning: git update of superproject %s failed, "
                     "repo sync will not use superproject to fetch source; "
-                    "while this error is not fatal, and you can continue to "
-                    "run repo sync, please run repo init with the "
-                    "--no-use-superproject option to stop seeing this warning",
+                    "this error is not fatal, and you can continue to "
+                    "run repo sync",
                     submanifest,
                 )
                 if sync_result.fatal and use_superproject is not None: