[202511][ssw] clean up DPU_APPL_DB and DPU_STATE_DB for DPU swss restart or DPU reboot

[zjswhhh]

Why I did it

For sonic-net/SONiC#2175

sign-off: Jing Zhang zhangjing@microsoft.com

Work item tracking

• Microsoft ADO (number only):

How I did it

1. Check if DPU_APPL_DB is pingable
2. If yes, flush all DB entries when swss starts.

How to verify it

Tested on ssw testbed.

• Entries got removed.

$ redis-cli -p 6381 -n 15 
127.0.0.1:6381[15]> keys *
1) "BFD_SESSION_TABLE:default:default:10.1.0.32"
2) "BFD_SESSION_TABLE:default:default:10.1.2.32"
3) "BFD_SESSION_TABLE:default:default:10.1.1.32"
127.0.0.1:6381[15]> keys *
(empty array)

$ redis-cli  -p 6381 MONITOR
OK

... ...
1769395816.952661 [18 169.254.200.1:34286] "PING"
1769395816.952718 [16 169.254.200.1:34280] "PING"
1769395816.954712 [17 169.254.200.1:34296] "SELECT" "17"
1769395816.954877 [17 169.254.200.1:34296] "PING"
1769395817.183169 [15 169.254.200.1:34310] "SELECT" "15"
1769395817.183386 [15 169.254.200.1:34310] "PING"
1769395817.210425 [15 169.254.200.1:34320] "SELECT" "15"
1769395817.210602 [15 169.254.200.1:34320] "FLUSHDB"
1769395817.229074 [17 169.254.200.1:34322] "SELECT" "17"
1769395817.229309 [17 169.254.200.1:34322] "FLUSHDB"

Which release branch to backport (provide reason below if selected)

• 202305
• 202311
• 202405
• 202411
• 202505
• 202511

Tested branch (Please provide the tested image version)

Description for the changelog

Link to config_db schema for YANG module changes

A picture of a cute animal (not mandatory but encouraged)

[mssonicbld]

/azp run Azure.sonic-buildimage

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[mssonicbld]

/azp run Azure.sonic-buildimage

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[mssonicbld]

/azp run Azure.sonic-buildimage

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