http: T5762: api: make API socket backend communication the one and o…

…nly default

Why: Smoketests fail as they can not establish IPv6 connection to uvicorn
backend server.

vyos/vyos-1x#2481 added a bunch of new smoketests.

While debugging those failing, it was uncovered, that uvicorn only listens on
IPv4 connections

vyos@vyos# netstat -tulnp | grep 8080
(Not all processes could be identified, non-owned process info
 will not be shown, you would have to be root to see it all.)
tcp        0      0 127.0.0.1:8080          0.0.0.0:*               LISTEN      -

As the CLI already has an option to move the API communication from an IP to a
UNIX domain socket, the best idea is to make this the default way of
communication, as we never directly talk to the API server but rather use the
NGINX reverse proxy.

docs/configuration/service/https.rst

@@ -20,23 +20,14 @@ Configuration
 
 .. cfgcmd:: set service https api debug
 
-   To enable debug messages. Available via :opcmd:`show log` or 
+   To enable debug messages. Available via :opcmd:`show log` or
    :opcmd:`monitor log`
 
-.. cfgcmd:: set service https api port
-
-   Set the listen port of the local API, this has no effect on the
-   webserver. The default is port 8080
-
-.. cfgcmd:: set service https api socket
-
-   Use local socket for API
-
 .. cfgcmd:: set service https api strict
 
    Enforce strict path checking
 
-.. cfgcmd:: set service https virtual-host <vhost> listen-address 
+.. cfgcmd:: set service https virtual-host <vhost> listen-address
             <ipv4 or ipv6 address>
 
    Address to listen for HTTPS requests