[NTP] When mgmtvrf is enabled, the NTP vrf should be changed to "mgmt"

[irene-pan1202]

What I did

#15058 Configure NTP global parameters, and specify the NTP vrf as "default". The NTP vrf does not change to "mgmt" when mgmtvrf is enabled, causing NTP create socket to fail.

ERR ntpd[34933]: bind(22) AF_INET 10.250.0.181#123 flags 0x19 failed: Cannot assign requested address
ERR ntpd[34933]: unable to create socket on eth0 (5) for 10.250.0.181#123

When mgmtvrf is enabled, the NTP vrf should be changed to "mgmt".

How I did it

How to verify it

Previous command output (if the output of a command-line utility has changed)

New command output (if the output of a command-line utility has changed)