Update Large Repo Import Workaround for LFS

Problem to solve

In workaround 2, we recommend importing a project without the repo, but this does not take LFS into account.

https://docs.gitlab.com/ee/user/project/settings/import_export_troubleshooting.html#workaround-option-2

Proposal

Add instructions on how to exclude and re-add LFS objects

Other links/references

Follow up to https://gitlab.com/gitlab-com/Product/-/issues/2645