remove `defer cancel()` calls inside a infinite `for` loop

[EclesioMeloJunior]

Issue summary

• At file dot/network/discovery.go the function checkPeerCount starts a looping to discover new peers at a defined amount of time, however, a new context is created inside the looping followed by the statement defer cancel() which is only called once the function exits
• This context is used by the findPeers as a timeout trigger, but this can be done inside the function using time.NewTimer(...) without the needed to use a context.

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