restructure java sdk output dir (keyvault)

[weidongxu-microsoft]

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Issue Azure/azure-sdk-for-java#5682
PR on sdk-for-java Azure/azure-sdk-for-java#5378
Target to move all generated java sdk into "sdk/" folder.

[AutorestCI]

Automation for azure-sdk-for-go

Nothing to generate for azure-sdk-for-go

[AutorestCI]

Automation for azure-sdk-for-python

Nothing to generate for azure-sdk-for-python

[azuresdkci]

Can one of the admins verify this patch?