tests: mock: Move hyperstart mock to virtcontainers
tests: mock: Move hyperstart mock to virtcontainers

This commit remove all code related to the hyperstart mock because
the same code has been added to virtcontainers project.
The proxy_test.go relying on this mock is now using the mock
from virtcontainers.

Signed-off-by: Sebastien Boeuf <90b401417360b1924ef3f520ddee932686110f85@intel.com>

clearcontainers/proxy,dlespiau/proxy,dlespiau/proxy,clearcontainers/proxy,dlespiau/clearcontainers-proxy,dlespiau/clearcontainers-proxy