No point looking for more than 3 headers here

https://github.com/apache/incubator-ponymail-foal/blob/fa674766cf555f4b0d5b6e895b2adccaf7984694/webui/js/source/body-fixups.js#L49-L50

AFAICT there is no point checking for more than 3 headers, as the next line would swallow them anyway.

There probably need to be some test cases.

Start with webui/js/source/body-fixups.js at lines 49-50 and read the surrounding header-processing logic. Add test cases covering header counts above three, then run the relevant test suite; done means the unnecessary checks are removed or bounded and the behavior remains covered by tests.

Written by the indexing model from the issue text.