Avoid extra storage bucket perm and query

Specifically, the `ListAllMyBuckets` permission.

This works if you know the directory exists.

See more:

* https://gitlab.com/gitlab-org/gitlab-ce/merge_requests/23981
* https://stackoverflow.com/a/12288581/1992201

lib/backup/manager.rb

@@ -195,7 +195,7 @@ module Backup
       if connection.service == ::Fog::Storage::Local
         connection.directories.create(key: remote_directory)
       else
-        connection.directories.get(remote_directory)
+        connection.directories.new(key: remote_directory)
       end
     end
 

spec/requests/api/runner_spec.rb

@@ -1320,7 +1320,7 @@ describe API::Runner, :clean_gitlab_redis_shared_state do
                 end
 
                 before do
-                  fog_connection.directories.get('artifacts').files.create(
+                  fog_connection.directories.new(key: 'artifacts').files.create(
                     key: 'tmp/uploads/12312300',
                     body: 'content'
                   )

spec/requests/lfs_http_spec.rb

@@ -1123,7 +1123,7 @@ describe 'Git LFS API and storage' do
 
                 context 'with valid remote_id' do
                   before do
-                    fog_connection.directories.get('lfs-objects').files.create(
+                    fog_connection.directories.new(key: 'lfs-objects').files.create(
                       key: 'tmp/uploads/12312300',
                       body: 'content'
                     )

spec/uploaders/file_uploader_spec.rb

@@ -201,7 +201,7 @@ describe FileUploader do
       end
 
       let!(:fog_file) do
-        fog_connection.directories.get('uploads').files.create(
+        fog_connection.directories.new(key: 'uploads').files.create(
           key: 'tmp/uploads/test/123123',
           body: 'content'
         )

spec/uploaders/object_storage_spec.rb

@@ -716,7 +716,7 @@ describe ObjectStorage do
           end
 
           let!(:fog_file) do
-            fog_connection.directories.get('uploads').files.create(
+            fog_connection.directories.new(key: 'uploads').files.create(
               key: 'tmp/uploads/test/123123',
               body: 'content'
             )