Snippet repository import fail with older export files

In #39201 (closed) we implemented the logic to export and import snippet with repositories. In the export logic, when the project snippets have repositories we create a snippets folder with all the repository bundles. If none of the snippets had a repository we still created that directory.

Nevertheless, in the import logic, we had the following clause at the beginning of the class that creates the snippet repository and commit the files: return true unless Dir.exist?(snippets_repo_bundle_path). This means that if the snippets folder is not found, we don't need to perform the snippet repository creation.

But there is a bug in this logic. For users using old (but valid) export files without the snippets directory, we won't create the snippet repository, leaving them without the possibility to use Git on them.

We can fix this by just removing the clause, allowing old exports, and generating all the snippets repository data.