Build automation should only open new milestones within the support window

[jzheaux]

The build automation opens a new point release each time it releases. It would be better to open ones within the support window.

To clarify with an example, the 5.8.x support window closes on 20 November 2023. By our normal cadence, 5.8.5 would release in August, and on that date, the automation would calculate the date for 5.8.6. Seeing that it is October and within the window, it would schedule it. However, in October, the automation would calculate a date of December and, seeing that's outside the window, would not schedule a 5.8.7.

I realize that has been common in the past for our team to schedule extra releases beyond the support window; however, since this is often a case-by-case basis, that's where I think the automation should stop. We can always manually schedule additional releases as necessary.