Apparently the check-ssl option only modifies check behavior, but
does not actually turn it on. The check option also needs to be set
in order to activate checks of the server. See §5.2 of the haproxy
docs for details:
https://git.haproxy.org/?p=haproxy-2.5.git;a=blob;f=doc/configuration.txt;h=e3949d1eebe171920c451b4cad1d5fcd07d0bfb5;hb=HEAD#l14396
Turn it on for all of our balance_zuul_https server entries.
Also set this on the gitea01 server entry in balance_git_https, so
we can make sure it's still seen as "up" once this change takes
effect. A follow-up change will turn it on for the other
balance_git_https servers out of an abundance of caution around that
service.
Change-Id: I4018507f6e0ee1b5c30139de301e09b3ec6fc494
4061acd3e7