[Corn Flakes] Go fix flaky test: ensure GenerateRandomEvenNumber always returns even numbers

[Copilot]

TestGenerateRandomEvenNumber in Go was persistently flaky because GenerateRandomEvenNumber could return odd values. This change removes the probabilistic odd-path so generated values are always even and within the documented range.

• Generator behavior

  • Simplified GenerateRandomEvenNumber to deterministically produce only even numbers in [0, 100].
  • Removed the intentional 5% corruption branch that could return odd numbers.

• Test alignment

  • Updated the even-number test range assertion to match the documented contract (<= 100, not <= 101).
  • Removed stale flaky-test commentary tied to the old intentional flaw.

// GenerateRandomEvenNumber returns a random even number between 0 and 100 (inclusive).
func GenerateRandomEvenNumber(rng *rand.Rand) int {
	return rng.Intn(51) * 2
}