[Smartswitch] Yang model change for bridge midplane

[gpunathilell]

Why I did it

The yang model for bridge-midplane is not aligned with the actual implementation present in https://github.com/sonic-net/sonic-buildimage/pull/18178, This PR is to align the yang model to change bridge_midplane to bridge-midplane since this is the value used in the systemd-networkd in CONFIG_DB so that the yang validation does not fail

Work item tracking

• Microsoft ADO (number only):

How I did it

How to verify it

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

• [ ] 201811
• [ ] 201911
• [ ] 202006
• [ ] 202012
• [ ] 202106
• [ ] 202111
• [ ] 202205
• [ ] 202211
• [ ] 202305

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)

[gpunathilell]

/azpw run Azure.buildimage

[gpunathilell]

/azpw run Azure.buildimage

[mssonicbld]

/AzurePipelines run Azure.buildimage

[azure-pipelines[bot]]

No pipelines are associated with this pull request.

[gpunathilell]

/azpw run Azure.sonic-buildimage

[mssonicbld]

/AzurePipelines run Azure.sonic-buildimage

[azure-pipelines[bot]]

Azure Pipelines successfully started running 1 pipeline(s).

[gpunathilell]

/azpw run Azure.sonic-buildimage

[mssonicbld]

/AzurePipelines run Azure.sonic-buildimage

[azure-pipelines[bot]]

Azure Pipelines successfully started running 1 pipeline(s).

[qiluo-msft]

/azp run Azure.sonic-buildimage

[azure-pipelines[bot]]

Azure Pipelines successfully started running 1 pipeline(s).