Remove unused autosubmit configuration file (#4410)

Remove autosubmit config files that are no longer being used. This was
from a previous design and not longer used.

List which issues are fixed by this PR. You must list at least one
issue.
Part of https://github.com/flutter/flutter/issues/130182

*If you had to change anything in the [flutter/tests] repo, include a
link to the migration guide as per the [breaking change policy].*

## Pre-launch Checklist

- [x] I read the [Contributor Guide] and followed the process outlined
there for submitting PRs.
- [x] I read the [Tree Hygiene] wiki page, which explains my
responsibilities.
- [x] I read and followed the [relevant style guides] and ran the
auto-formatter. (Unlike the flutter/flutter repo, the flutter/packages
repo does use `dart format`.)
- [x] I signed the [CLA].
- [ ] The title of the PR starts with the name of the package surrounded
by square brackets, e.g. `[shared_preferences]`
- [x] I listed at least one issue that this PR fixes in the description
above.
- [ ] I updated `pubspec.yaml` with an appropriate new version according
to the [pub versioning philosophy], or this PR is [exempt from version
changes].
- [ ] I updated `CHANGELOG.md` to add a description of the change,
[following repository CHANGELOG style].
- [ ] I updated/added relevant documentation (doc comments with `///`).
- [x] I added new tests to check the change I am making, or this PR is
[test-exempt].
- [x] All existing and new tests are passing.

If you need help, consider asking for advice on the #hackers-new channel
on [Discord].

<!-- Links -->
[Contributor Guide]:
https://github.com/flutter/packages/blob/main/CONTRIBUTING.md
[Tree Hygiene]: https://github.com/flutter/flutter/wiki/Tree-hygiene
[relevant style guides]:
https://github.com/flutter/packages/blob/main/CONTRIBUTING.md#style
[CLA]: https://cla.developers.google.com/
[flutter/tests]: https://github.com/flutter/tests
[breaking change policy]:
https://github.com/flutter/flutter/wiki/Tree-hygiene#handling-breaking-changes
[Discord]: https://github.com/flutter/flutter/wiki/Chat
[pub versioning philosophy]: https://dart.dev/tools/pub/versioning
[exempt from version changes]:
https://github.com/flutter/flutter/wiki/Contributing-to-Plugins-and-Packages#version-and-changelog-updates
[following repository CHANGELOG style]:
https://github.com/flutter/flutter/wiki/Contributing-to-Plugins-and-Packages#changelog-style
[test-exempt]:
https://github.com/flutter/flutter/wiki/Tree-hygiene#tests

.github/autosubmit.yml

@@ -1,7 +0,0 @@
-# Copyright 2023 The Flutter Authors. All rights reserved.
-# Use of this source code is governed by a BSD-style license that can be
-# found in the LICENSE file.
-
-# This file will be added to flutter's internal repository.
-# https://github.com/flutter/flutter/wiki/Autosubmit-bot
-config_path: 'autosubmit/flutter/autosubmit_main.yml'