fix: healthcheckv2extension: fix deadlock in case of an error in http server start

[lim123123123]

Description

The current implementation uses a channel for graceful shutdown, but it doesn't work in case of an error during socket binding. Since the goroutine that writes to that channel is never created, it causes a deadlock in Shutdown.

This is a minor issue, but it annoys me. Each time I forget to shut down the previous debug session, the new one freezes (since the address is already in use, causing an error in Start).

Link to tracking issue

Fixes
Since this is a really small problem, I didn't create an issue. Let me know if it's required, and I'll create one.

Testing

I've added a unit test that fails with the current implementation but works with the fix.

[linux-foundation-easycla]

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