Fix disabled dockerfiles
When the dockerfiles were moved into the host-x86_64 directory, paths
for COPY commands were updated with the new host-x86_64/ prefix. This
suggested that the intended context was src/ci/docker. However, the context
for disabled docker images was src/ci/docker/host-x86_64. This broke the new
paths and prevented src/ci/docker/scripts from being included in the
context at all.
This commit corrects this context allowing docker to find the files it
needs for COPY commands.
Also includes a quick fix to riscv recommended by @bjorn3
8376fcd5ce