mgmt eng, keep premium samples in place

[XiaofeiCao]

Description

• part of mgmt premium, keep premium samples in individual packages, instead of moving under azure-resourcemanager #47621
• pending on emitter update/release: mgmt, use separate entry points for premium samples microsoft/typespec#9845

This PR does:

1. Remove logic to copy premium samples from individual packages to sdk/resourcemanager/azure-resourcemanager
2. Remove logic to add unreleased entry in version_client.txt and use unreleased version in azure-resourcemanager

The changes include both Swagger and TypeSpec generation. Tested locally for both.

If an SDK is being regenerated based on a new swagger spec, a link to the pull request containing these swagger spec changes has been included above.

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• The pull request does not introduce [breaking changes]
• CHANGELOG is updated for new features, bug fixes or other significant changes.
• I have read the contribution guidelines.

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