Remove Group file import from the New Group creation flow
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## Problem to solve
With the [deprecation](https://gitlab.com/gitlab-org/gitlab/-/issues/332957) of the [Group Export/Import](https://docs.gitlab.com/ee/user/group/settings/import_export.html) functionality, we need to remove the ability to import a file containing a group export.
## Proposed solution
Remove the option to "import group from file" during the [New Group creation flow](https://gitlab.com/groups/new#import-group-pane). The only option to import a group should be using GitLab Migration.
## Illustrations

## Further considerations
* Remove ability to export groups from UI - https://gitlab.com/gitlab-org/gitlab/-/issues/341282
* Remove the ability to export groups using API - **issue needed**
* Remove the ability to import a group file using API - **issue needed**
## Documentation
* :book: [Group Export/Import](https://docs.gitlab.com/ee/user/group/settings/import_export.html)
* :book: [GitLab Migration](https://docs.gitlab.com/ee/user/group/import/)
issue