[gitlab-org/gitlab] Add offline transfer as an import source

### ROOT CAUSE The issue arises because the `Import::HasImportSource` concern does not recognize `:offline_transfer` as a valid import source. Without this, logs generated during offline transfers are not properly categorized, leading to potential confusion with other transfer logs. ### CODE FIX To address this, we'll add `:offline_transfer` to the list of valid import sources in the `Import::HasImportSource` concern. **Step-by-step Explanation:** 1. **Locate the Valid Import Sources:** Find where valid import sources are defined in `app/models/concerns/import/has_import_source.rb`. 2. **Add `:offline_transfer`:** Include `:offline_transfer` in the array of valid sources. 3. **Update the Concern:** Ensure the concern correctly handles the new source for logging. **Code Fix:**

ruby
# app/models/concerns/import/has_import_source.rb

module Import
  class HasImportSource
    extend ActiveSupport::Concern

    VALID_IMPORT_SOURCES = %w[
      direct_upload
      scheduled_import
      background_import
      manual_import
      incremental_import
      bulk_import
      offline_transfer
    ].freeze

    # ... rest of the code
  end
end


This change adds `:offline_transfer` as a recognized import source, ensuring proper logging and classification.