fix server if agent get hostname is same, vm table will update, not add

[LeoDemoniac]

This PR is for:

• Server [x]

In a certain scenario, we add a legacy-host (follow this doc legacy-host). We had some same hostname x86 agents,eg: localhost, we found Mysql table vm and vtap got only one agent, and the device_id is same(in the agents who have same hostname), found the hostname is the issue, so we add peer and - prefix the hostname。

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