Direct disk access is done through Gitaly now, so the legacy path was
deprecated. This path was used in Gitlab::Shell however. This required
the refactoring in this commit.
Added is the removal of direct path access on the project model, as that
lookup wasn't needed anymore is most cases.
Closes https://gitlab.com/gitlab-org/gitaly/issues/1111
If the source import directory were different from the destination directory,
GitLab would first create a blank repository and then erroneously move the
original one into a subdirectory. Adding an import type prevents this the project
from being initialized in the first place. It was accidentally removed in
1f917cbd49.
Closes#40765
