Fix GH-7781: CLI server prints HTML in startup warnings

[matthiasgoergens]

Startup diagnostics of the built-in server were formatted as HTML because the CLI server keeps html_errors on for request handling and used the same setting before the listening socket existed. Suppress the displayed resolver warning around the listen call: its text is already repeated as the reason in the server's own "Failed to listen" message.

Fixes GH-7781.

[devnexen]

why not acting on display_errors instead ? e.g.

     ...
     uint8_t display_errors = PG(display_errors);
     PG(display_errors) = 0;
     /// note: php_cli_server_ctor() reports its own failures through php_cli_server_logf()
     server_ctor_result = php_cli_server_ctor(&server, server_bind_address, document_root, router);
     PG(display_errors) = display_errors;
     ...

[matthiasgoergens]

Thanks, that is cleaner. The resolver warning's text is exactly what php_cli_server_ctor() prints as the reason: of its "Failed to listen" message, so suppressing the displayed copy just drops the duplicate:

before:  Warning: Unknown: php_network_getaddresses: getaddrinfo for 0.0..0 failed: Name or service not known in Unknown on line 0
         [...] Failed to listen on 0.0..0:8080 (reason: php_network_getaddresses: getaddrinfo for 0.0..0 failed: Name or service not known)
after:   [...] Failed to listen on 0.0..0:8080 (reason: php_network_getaddresses: getaddrinfo for 0.0..0 failed: Name or service not known)

I put the display_errors toggle around php_network_listen_socket() rather than the whole constructor, so that worker startup (which can raise its own errors) is not covered. The existing error-logging behaviour is unchanged. The test now expects empty stdout and the reason on stderr.