Update description for placement in create/update/get parameters

[kunyilin-msft]

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[github-actions]

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[github-actions]

API Change Check

APIView identified API level changes in this PR and created the following API reviews

Language	API Review for Package
Swagger	Microsoft.Storage
Go	sdk/resourcemanager/storage/armstorage
Java	com.azure.resourcemanager:azure-resourcemanager-storage-generated
JavaScript	@azure/arm-storage

[blueww]

There's also a new API version 2025-06-01 PR in review.
#37597

If the change is needed, it should also apply to that new API version.

[yifanz7]

Do we also want to update the descriptions in storage account update parameters? https://github.com/Azure/azure-rest-api-specs/blob/main/specification/storage/resource-manager/Microsoft.Storage/stable/2025-01-01/storage.json#L4547-L4556