Do not install internal scripts in /usr/bin

build-ha-guide.sh and markdown-docbook.sh are only needed by doctest.py,
so make them only available to that tool. There's no need to install
these files in /usr/bin.

Change-Id: Idd2f40dbe0a50a0936311574a26553444a4dd7e1
Merge "Do not install internal scripts in /usr/bin"