T6934: Add preshared key for zabbix-agent monitoring service

- Allow configure preshared key for zabbix-agent
- Added op mode command for generatre random psk secret
- Removed duplicate xml definition for psk settings


Configure authentication mode:
```
# set service monitoring zabbix-agent authentication mode
Possible completions:
   pre-shared-secret    Use a pre-shared secret key
```

Configure PSK Settings:
```
# set service monitoring zabbix-agent authentication psk
Possible completions:
   id                   ID for authentication
   secret               pre-shared secret key

```

Generate Random PSK:
```
$ generate psk random
Possible completions:
  <Enter>               Execute the current command
  size                  Key size in bytes

```

1 files changed, 1 insertions, 12 deletions

diff --git a/interface-definitions/vpn_ipsec.xml.in b/interface-definitions/vpn_ipsec.xml.in
index 5540021e2..0cf526fad 100644
--- a/interface-definitions/vpn_ipsec.xml.in
+++ b/interface-definitions/vpn_ipsec.xml.in
@@ -722,18 +722,7 @@
                   <help>Authentication</help>
                 </properties>
                 <children>
-                  <leafNode name="mode">
-                    <properties>
-                      <help>Authentication mode</help>
-                      <completionHelp>
-                        <list>pre-shared-secret</list>
-                      </completionHelp>
-                      <valueHelp>
-                        <format>pre-shared-secret</format>
-                        <description>Use a pre-shared secret key</description>
-                      </valueHelp>
-                    </properties>
-                  </leafNode>
+                  #include <include/auth-mode-pre-shared-secret.xml.i>
                   #include <include/ipsec/authentication-pre-shared-secret.xml.i>
                 </children>
               </node>