Fix link to URL for image of FECA used on statutes page

[dorothyyeager]

Summary

What we are after:
When I uploaded the new thumbnail of the FECA, I didn't realize that the statutes page was pulling off a static link. Right now the image is not working. @patphongs has figured it out and knows how to fix this.

Related issues

• PR for changing out image - https://github.com/fecgov/fec-cms/pull/3334/files

Note: Image we want has been uploaded to cms at https://www.fec.gov/resources/cms-content/images/52usc.original.png and to dev at https://fec-dev-proxy.app.cloud.gov/resources/cms-content/images/52usc.original.original.png (I don't know why dev is adding original twice into the file name)

I'll attach here too in case you need to reupload

Completion criteria

• Adjust the "document thumbnail" coding in the jinja file to take the "static" out of the image URL
• Test this on stage after release