Index file name even if file size is beyond the max file size limit

Summary

References #76 (closed)

This will index files (without the content) even if the file size is above the max file size limit. The content sent will be an empty string.

Updated tests and fixed a locally failing spec with some details on why.

How to test

I setup gdk to use this version of the gitlab-elasticsearch-indexer and added a file that was larger than the max file size limit. It successfully indexed the file with blank content.