BUG/MINOR: server: Update healthcheck when server settings are changed via CLI

BUG/MINOR: server: Update healthcheck when server settings are changed via CLI

not all changes are concerned. But when the SSL is enabled or disabled for a
server, the healthcheck xprt must be eventually be updated too. This happens
when the healthcheck relies on the server settings.

In the same spirit, when the healthcheck address and port are updated, we
must fallback on the raw xprt if the SSL is not explicitly enabled for the
healthcheck with a "check-ssl" parameter.

This patch should be backported to all stable versions.