Merge branch 'fix/sm/hard-reset-for-use-file' into 'master'

Fix broken `use_file` method

Closes #4827

See merge request gitlab-org/gitlab-ee!4836

ee/app/uploaders/object_storage.rb

@@ -241,6 +241,7 @@ module ObjectStorage
         cache_stored_file!
         yield cache_path
       ensure
+        FileUtils.rm_f(cache_path)
         cache_storage.delete_dir!(cache_path(nil))
       end
     end

ee/spec/uploaders/object_storage_spec.rb

@@ -189,6 +189,18 @@ describe ObjectStorage do
           it "calls a cache path" do
             expect { |b| uploader.use_file(&b) }.to yield_with_args(%r[tmp/cache])
           end
+
+          it "cleans up the cached file" do
+            cached_path = ''
+
+            uploader.use_file do |path|
+              cached_path = path
+
+              expect(File.exist?(cached_path)).to be_truthy
+            end
+
+            expect(File.exist?(cached_path)).to be_falsey
+          end
         end
       end