feat: add graceful shutdown for healthy-check http server.

[fengruotj]

The same as this pr: volcano-sh/volcano#4285.

StartHealthz() provides health checks for volcano-controller, volcano-admission, and volcano-scheduler.

Regarding the stop channel returned from signal handling: if multiple handlers are waiting on different channels, only one of them will be triggered. Therefore, we must use signals.SetupSignalContext() to handle signals, as it will close the signal channel, allowing multiple handlers to be triggered simultaneously.

[volcano-sh-bot]

Welcome @fengruotj!

It looks like this is your first PR to volcano-sh/apis.

Thank you, and welcome to Volcano. 😃

[volcano-sh-bot]

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[fengruotj]

Why i got the following message:
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[fengruotj]

/assign @hwdef

[fengruotj]

PTAL, makes code strong & elegance together .

[fengruotj]

/assign @k82cn