bgpd: Do not explicitly print MAXTTL value for ebgp-multihop vty output

1. Create /etc/frr/frr.conf
```
frr version 7.5
frr defaults traditional
hostname centos8.localdomain
no ip forwarding
no ipv6 forwarding
service integrated-vtysh-config
line vty
router bgp 4250001000
  neighbor 192.168.122.207 remote-as 65512
  neighbor 192.168.122.207 ebgp-multihop
```

2. Start FRR
`# systemctl start frr
`
3. Show running configuration. Note that FRR explicitly set and shows the default TTL (225)

```
Building configuration...

Current configuration:
!
frr version 7.5
frr defaults traditional
hostname centos8.localdomain
no ip forwarding
no ipv6 forwarding
service integrated-vtysh-config
!
router bgp 4250001000
 neighbor 192.168.122.207 remote-as 65512
 neighbor 192.168.122.207 ebgp-multihop 255
!
line vty
!
end
```
4. Copy initial frr.conf to frr.conf.new (no changes)
`# cp /etc/frr/frr.conf /root/frr.conf.new
`
5. Run frr-reload.sh:

```
$ /usr/lib/frr/frr-reload.py --test  /root/frr.conf.new
2023-08-20 20:15:48,050  INFO: Called via "Namespace(bindir='/usr/bin', confdir='/etc/frr', daemon='', debug=False, filename='/root/frr.conf.new', input=None, log_level='info', overwrite=False, pathspace=None, reload=False, rundir='/var/run/frr', stdout=False, test=True, vty_socket=None)"
2023-08-20 20:15:48,050  INFO: Loading Config object from file /root/frr.conf.new
2023-08-20 20:15:48,124  INFO: Loading Config object from vtysh show running

Lines To Delete
===============
router bgp 4250001000
 no neighbor 192.168.122.207 ebgp-multihop 255

Lines To Add
============
router bgp 4250001000
 neighbor 192.168.122.207 ebgp-multihop
```

Closes #14242

Signed-off-by: Donatas Abraitis <[email protected]>

bgpd/bgp_vty.c

@@ -17735,8 +17735,12 @@ static void bgp_config_write_peer_global(struct vty *vty, struct bgp *bgp,
 	    && !(peer->gtsm_hops != BGP_GTSM_HOPS_DISABLED
 		 && peer->ttl == MAXTTL)) {
 		if (!peer_group_active(peer) || g_peer->ttl != peer->ttl) {
-			vty_out(vty, " neighbor %s ebgp-multihop %d\n", addr,
-				peer->ttl);
+			if (peer->ttl != MAXTTL)
+				vty_out(vty, " neighbor %s ebgp-multihop %d\n",
+					addr, peer->ttl);
+			else
+				vty_out(vty, " neighbor %s ebgp-multihop\n",
+					addr);
 		}
 	}