Rollup merge of #74161 - tblah:riscv64gc-dockerfile-improvment, r=Mark-Simulacrum

Rollup merge of #74161 - tblah:riscv64gc-dockerfile-improvment, r=Mark-Simulacrum

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