zebra: Fix missing VRF flag

zebra: Fix missing VRF flag

1. No any configuration in FRR, and `ip link add vrf1 type vrf ...`.
Currently, everything is ok.

2.  `ip link del vrf1`.
`zebra` will wrongly/redundantly notify clients to add "vrf1" as a normal
interface after correct deletion of "vrf1".

```
ZEBRA: [KMXEB-K771Y] netlink_parse_info: netlink-listen (NS 0) type RTM_DELLINK(17), len=588, seq=0, pid=0
ZEBRA: [TDJW2-B9KJW] RTM_DELLINK for vrf1(93) <- Wrongly as normal interface, not vrf
ZEBRA: [WEEJX-M4HA0] interface vrf1 vrf vrf1(93) index 93 is now inactive.
ZEBRA: [NXAHW-290AC] MESSAGE: ZEBRA_INTERFACE_DELETE vrf1 vrf vrf1(93)
ZEBRA: [H97XA-ABB3A] MESSAGE: ZEBRA_INTERFACE_VRF_UPDATE/DEL vrf1 VRF Id 93 -> 0
ZEBRA: [HP8PZ-7D6D2] MESSAGE: ZEBRA_INTERFACE_VRF_UPDATE/ADD vrf1 VRF Id 93 -> 0 <-
ZEBRA: [Y6R2N-EF2N4] interface vrf1 is being deleted from the system
ZEBRA: [KNFMR-AFZ53] RTM_DELLINK for VRF vrf1(93)
ZEBRA: [P0CZ5-RF5FH] VRF vrf1 id 93 is now inactive
ZEBRA: [XC3P3-1DG4D] MESSAGE: ZEBRA_VRF_DELETE vrf1
ZEBRA: [ZMS2F-6K837] VRF vrf1 id 4294967295 deleted
OSPF: [JKWE3-97M3J] Zebra: interface add vrf1 vrf default[0] index 0 flags 480 metric 0 mtu 65575 speed 0 <- Wrongly add interface
```

`if_handle_vrf_change()` moved the interface from specific vrf to default
vrf. But it doesn't skip interface of vrf type. So, the wrong/redundant
add operation is done.

Note, the wrong add operation is regarded as an normal interface because
the `ifp->status` is cleared too early, so it is without VRF flag
( `ZEBRA_INTERFACE_VRF_LOOPBACK` ). Now, ospfd will initialize `ifp->type`
to `OSPF_IFTYPE_BROADCAST`.

3. `ip link add vrf1 type vrf ...`, add "vrf1" again. FRR will be with
wrong display:

```
interface vrf1
 ip ospf network broadcast
exit
```

Here, zebra will send `ZEBRA_INTERFACE_ADD` again for "vrf1" with
correct `ifp->status`, so it will be updated into vrf type. But
it can't update `ifp->type` from `OSPF_IFTYPE_BROADCAST` to
`OSPF_IFTYPE_LOOPBACK` because it had been already configured in above
step 2.

Two changes to fix it:

1. Skip the procedure of switching VRF for interfaces of vrf type.
It means, don't send `ZEBRA_INTERFACE_ADD` to clients when deleting vrf.

2. Put the deletion of this flag at the last.
It means, clients should get correct `ifp->status`.

Signed-off-by: anlan_cs <vic.lan@pica8.com>