FDB table is not cleared during cold swss start

[stepanblyschak]

Description
FDB table is not cleared during cold swss start

Steps to reproduce the issue:

1. Run VLAN-TRUNK test
2. config reload -y
3. redis-cli -n 6 keys FDB

Describe the results you received:

admin@arc-switch1025:~$ redis-cli -n 6 keys *FDB*
 1) "FDB_TABLE|Vlan100:52:54:00:83:2f:8f"
 2) "FDB_TABLE|Vlan1000:52:54:00:e9:bc:6c"
 3) "FDB_TABLE|Vlan100:5a:ee:b8:10:a3:1c"
 4) "FDB_TABLE|Vlan100:ca:5d:7f:95:98:1e"
 5) "FDB_TABLE|Vlan200:e4:1d:2d:ca:c7:02"
 6) "FDB_TABLE|Vlan1000:52:54:00:f8:bb:45"
 7) "FDB_TABLE|Vlan1000:52:54:00:05:d3:94"
 8) "FDB_TABLE|Vlan200:52:54:00:88:53:31"
 9) "FDB_TABLE|Vlan1000:52:54:00:2e:7c:70"
10) "FDB_TABLE|Vlan100:e4:1d:2d:ca:c7:02"
11) "FDB_TABLE|Vlan200:5a:ee:b8:10:a3:1c"
12) "FDB_TABLE|Vlan1000:e4:1d:2d:ca:c7:14"
13) "FDB_TABLE|Vlan200:e4:1d:2d:ca:c7:01"
14) "FDB_TABLE|Vlan1000:52:54:00:45:78:f7"
15) "FDB_TABLE|Vlan200:00:22:00:00:00:02"
16) "FDB_TABLE|Vlan1000:52:54:00:ba:d3:82"
17) "FDB_TABLE|Vlan100:00:22:00:00:00:02"
18) "FDB_TABLE|Vlan200:ca:5d:7f:95:98:1e"
19) "FDB_TABLE|Vlan1000:52:54:00:96:1f:8a"
20) "FDB_TABLE|Vlan100:e4:1d:2d:ca:c7:01"
21) "FDB_TABLE|Vlan1000:52:54:00:92:26:57"
22) "FDB_TABLE|Vlan1000:e4:1d:2d:ca:c7:0a"
23) "FDB_TABLE|Vlan1000:52:54:00:22:30:8b"

admin@arc-switch1025:~$ redis-cli -n 0 keys *VLAN_TABLE*
1) "VLAN_TABLE:Vlan1000"

Describe the results you expected:

No FDB entries referencing non-existing interfaces

Additional information you deem important (e.g. issue happens only occasionally):

**Output of `show version`:**

```
admin@arc-switch1025:~$ show version

SONiC Software Version: SONiC.HEAD.60-bd7b96f
Distribution: Debian 9.9
Kernel: 4.9.0-8-amd64
Build commit: bd7b96f
Build date: Mon May 20 02:23:56 UTC 2019
Built by: johnar@jenkins-worker-4

Docker images:
REPOSITORY TAG IMAGE ID SIZE
docker-orchagent-mlnx HEAD.60-bd7b96f 77b2febc6eb5 286MB
docker-orchagent-mlnx latest 77b2febc6eb5 286MB
docker-syncd-mlnx HEAD.60-bd7b96f d1b37656c622 331MB
docker-syncd-mlnx latest d1b37656c622 331MB
docker-lldp-sv2 HEAD.60-bd7b96f 2d29faeaffaf 274MB
docker-lldp-sv2 latest 2d29faeaffaf 274MB
docker-dhcp-relay HEAD.60-bd7b96f a622e4e9bc81 256MB
docker-dhcp-relay latest a622e4e9bc81 256MB
docker-database HEAD.60-bd7b96f 123cfec31f3c 255MB
docker-database latest 123cfec31f3c 255MB
docker-snmp-sv2 HEAD.60-bd7b96f 9bafa58e73fa 289MB
docker-snmp-sv2 latest 9bafa58e73fa 289MB
docker-teamd HEAD.60-bd7b96f 394ebacb3c82 274MB
docker-teamd latest 394ebacb3c82 274MB
docker-router-advertiser HEAD.60-bd7b96f 5325177d1b26 254MB
docker-router-advertiser latest 5325177d1b26 254MB
docker-platform-monitor HEAD.60-bd7b96f e705c8c67822 286MB
docker-platform-monitor latest e705c8c67822 286MB
docker-fpm-quagga HEAD.60-bd7b96f 15b215afce5a 281MB
docker-fpm-quagga latest 15b215afce5a 281MB

```

**Attach debug file `sudo generate_dump`:**

```
(paste your output here)
```