DOC: fix a few remainig cases of "Haproxy" and "HAproxy" in doc and comments

DOC: fix a few remainig cases of "Haproxy" and "HAproxy" in doc and comments

Some of the Lua doc and a few places still used "Haproxy" or "HAproxy".
There was even one "HA proxy". A few of them were in an example of VTest
output, indicating that VTest ought to be fixed as well. No big deal but
better address all the remaining ones so that these inconsistencies stop
spreading around.