codehosting-lb haproxy configuration is not updated when haproxy configuration options in the launchpad-codehosting charm are changed

[Guruprasad]

The launchpad-codehosting charm has `haproxy_*` configuration options to tweak the haproxy configuration in the related codehosting-lb unit. But when the values for these options are modified, the associated haproxy configuration in the codehosting-lb unit does not get changed.