Remove ROUTER_BIND_PORTS_BEFORE_SYNC configuration

[ironcladlou]

The ROUTER_BIND_PORTS_BEFORE_SYNC option was added and the liveness checks it
gates was enabled by default. We don't have any strong use case to support
making it configurable. Remove the option to reduce our configuration surface
area.

Fixes https://bugzilla.redhat.com/show_bug.cgi?id=1603835.

/cc @openshift/sig-network-edge

[Miciah]

I think the conditional is broken but necessary. The intention is to omit the "backend" (HAProxy) check from the liveness checks if ROUTER_BIND_PORTS_AFTER_SYNC is enabled in order to prevent the liveness checks from failing during the period between when the router pod starts and when HAProxy starts responding to its liveness check (after sync). See #19009 (comment).

[ironcladlou]

@Miciah is right, I got this wrong. New PR necessary.