Log disk_path instead of path for importer

The importer uses the correct logic to avoid accessing
`Repository#path`, though not  when logging. As such we log the
disk_path now to avoid an error in production.

Note this logline created failures in production and this commit
contains a bugfix.

lib/gitlab/import_export/repo_restorer.rb

@@ -42,7 +42,7 @@ module Gitlab
       def ensure_repository_does_not_exist!
         if repository.exists?
           shared.logger.info(
-            message: %Q{Deleting existing "#{repository.path}" to re-import it.}
+            message: %Q{Deleting existing "#{repository.disk_path}" to re-import it.}
           )
 
           Repositories::DestroyService.new(repository).execute

spec/lib/gitlab/import_export/repo_restorer_spec.rb

@@ -46,7 +46,7 @@ RSpec.describe Gitlab::ImportExport::RepoRestorer do
     context 'when the repository already exists' do
       it 'deletes the existing repository before importing' do
         allow(project.repository).to receive(:exists?).and_return(true)
-        allow(project.repository).to receive(:path).and_return('repository_path')
+        allow(project.repository).to receive(:disk_path).and_return('repository_path')
 
         expect_next_instance_of(Repositories::DestroyService) do |instance|
           expect(instance).to receive(:execute).and_call_original