BUG/MEDIUM: ssl/cli: abort ssl cert is freeing the old store

The "abort ssl cert" command is buggy and removes the current ckch store,
and instances, leading to SNI removal. It must only removes the new one.

This patch also adds a check in set_ssl_cert.vtc and
set_ssl_server_cert.vtc.

Must be backported as far as 2.2.
3 files changed