[12.x] Prevent unintended sleep on early failure of assertSequence

[xHeaven]

When Sleep::assertSequence is given Sleep instances as "expected" values and

1. the count assertion fails or
2. one of the duration checks fail (since we are going one by one via each)

the remaining Sleep objects can execute their destructors before they’ve been marked as "do not sleep".

This makes the tests run for a longer time than expected because the remaining Sleep objects will actually sleep, even though this is unintended.

Reproduction:

/**
 * Expected runtime: instant
 * Actual runtime: 3 seconds
 * Reason: in the `each` call, the first instance will fail the test, therefore
 * the second instance won't be marked as "do not sleep" - it will sleep
 */
it('will fail the first iteration', function () {
    Sleep::fake();

    Sleep::sleep(3);
    Sleep::sleep(3);

    Sleep::assertSequence([
        Sleep::sleep(3.1),
        Sleep::sleep(3),
    ]);
});

/**
 * Expected runtime: instant
 * Actual runtime: 3 seconds
 * Reason: the count assertion fails, no instance will be marked as "do not sleep" - they will sleep
 */
it('will fail the count assertion', function () {
    Sleep::fake();

    Sleep::sleep(3);
    Sleep::sleep(3);

    Sleep::assertSequence([
        Sleep::sleep(3),
    ]);
});

[xHeaven]

I think the failing test is unrelated to this PR, just fyi.