Fix TestResendEncryptionKeyOnBackupRestore test wait condition

[mprakhov]

Problem

TestResendEncryptionKeyOnBackupRestore contains empty wait condition

// FIXME: `HandleCommunityEncryptionKeysRequest` does not return any response
// ad-hoc solution - wait for `WaitOnMessengerResponse` timeout
_, _ = WaitOnMessengerResponse(s.owner,
	func(r *MessengerResponse) bool {
		return false
	},
	"no community that satisfies criteria",
)

We can treat it as sleep(10)

Need to find a way how to understand, that keys were resent in HandleCommunityEncryptionKeysRequest from the owner side

Note: Good if we find a universal solution in order to use it with other handlers, which does not send any response