[Bugfix][MetaSchedule] RPC port needs to be an integer

[junrushao]

This PR introduces a bugfix where the RPC port could be mistakenly detected as a string from environment variables, which is required to be an integer for subsequent operators. We cast the type to int in auto detection.

[tvm-bot]

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• cc @ibsidorenko _{See #10317 for details}

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