[mlag]Fix dynamic local fdb not save to state db

[pettershao-ragilenetworks]

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What I did Fix dynamic local fdb not save to state db, issue is as below:

1. Dual access for mlag
2. active peer learn mac, stanby sync mac, so stanby device's fdb is static
3. active peer mlag interface shutdown, so acitve device's fdb convert to peer link and static, stanby's fdb switch to dynamic
4. clear fdb in stanby, issue appear, asic db cleared, but iccpd still exist fdb entry, either do acitve device.

Why I did it If dynamic local fdb not save to state db, then clear fdb will fail to remove fdb entry in state db and iccpd will not got clear notification, fdb entry in iccpd will not sync with asic db, and peer device's fdb will not remove either. How I verified it clear fdb all Details if related

[pettershao-ragilenetworks]

@prsunny @Praveen-Brcm help check and forward this, thanks!

[pettershao-ragilenetworks]

@prsunny help forward this, thanks!

[pettershao-ragilenetworks]

check newest test case:test_mclagFdb_remote_to_local has passed.

[pettershao-ragilenetworks]

@qiluo-msft @lguohan help merge this, thanks!

[pettershao-ragilenetworks]

@gechiang help forward this, thanks!

[gechiang]

/azp run

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