Containers have been refactored to use the same serve method as other packages, ensuring consistent response handling.
fixes#7888
## Checklist
The [contributor guide](https://forgejo.org/docs/next/contributor/) contains information that will be helpful to first time contributors. There also are a few [conditions for merging Pull Requests in Forgejo repositories](https://codeberg.org/forgejo/governance/src/branch/main/PullRequestsAgreement.md). You are also welcome to join the [Forgejo development chatroom](https://matrix.to/#/#forgejo-development:matrix.org).
### Tests
- I added test coverage for Go changes...
- [ ] in their respective `*_test.go` for unit tests.
- [x] in the `tests/integration` directory if it involves interactions with a live Forgejo server.
- I added test coverage for JavaScript changes...
- [ ] in `web_src/js/*.test.js` if it can be unit tested.
- [ ] in `tests/e2e/*.test.e2e.js` if it requires interactions with a live Forgejo server (see also the [developer guide for JavaScript testing](https://codeberg.org/forgejo/forgejo/src/branch/forgejo/tests/e2e/README.md#end-to-end-tests)).
### Documentation
- [ ] I created a pull request [to the documentation](https://codeberg.org/forgejo/docs) to explain to Forgejo users how to use this change.
- [x] I did not document these changes and I do not expect someone else to do it.
### Release notes
- [ ] I do not want this change to show in the release notes.
- [x] I want the title to show in the release notes with a link to this pull request.
- [ ] I want the content of the `release-notes/<pull request number>.md` to be be used for the release notes instead of the title.
<!--start release-notes-assistant-->
## Release notes
<!--URL:https://codeberg.org/forgejo/forgejo-->
- Bug fixes
- [PR](https://codeberg.org/forgejo/forgejo/pulls/8037): <!--number 8037 --><!--line 0 --><!--description b21pdCBDb250ZW50LUxlbmd0aCBvbiAzMDcgcmVkaXJlY3RzIHdoZW4gc2VydmluZyBkaXJlY3QgbWFuaWZlc3QgZm9yIGNvbnRhaW5lcnM=-->omit Content-Length on 307 redirects when serving direct manifest for containers<!--description-->
<!--end release-notes-assistant-->
Reviewed-on: https://codeberg.org/forgejo/forgejo/pulls/8037
Reviewed-by: Earl Warren <earl-warren@noreply.codeberg.org>
Co-authored-by: Julian Schlarb <julian.schlarb@denktmit.de>
Co-committed-by: Julian Schlarb <julian.schlarb@denktmit.de>
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