[dualtor-aa] ToR local state stuck in standby

[zjswhhh]

Description

Steps to reproduce the issue:

1. Change mux mode -> standby for maintenance, default route == 'na"
2. socnet agent restart
3. socnet agent up with admin state as "active"
4. ToR tries to restore standby state
   
5. switchMuxState skipped for mux mode not being auto
6. maintenance finishes, mux mode -> auto, default route -> ok
7. switch over to active didn't trigger cause last mux notification wasn't Unknown
   

Describe the results you received:

Describe the results you expected:

Output of show version:

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

[prgeor]

@lolyu seems you already working on the fix. @yxieca fyi

[lolyu]

This should be fixed by @zjswhhh cc @prgeor