Do not change the changewave optout

[JanKrivanek]

Motivation

ChangeWave optout should be tailored to optout of a specific behavior - let's not "auto-bump" the optout to newer waves automatically. This can lead to unexpected changes in behavior

Sample case

##[warning]Environment variable MSBUILDDISABLEFEATURESFROMVERSION is set to a version that is out of rotation. Defaulting to Change Wave version: 17.10. Entered value: 17.6. Current Change Waves: [17.10, 17.12].

Expected Behavior

Specifying old changewave doesn't have any effect

Actual behavior

Specifying old changewave opts out of newer behavior

[JanKrivanek]

Discussed offline with @rainersigwald - we cannot simply change the behavior as there might be existing users explicitly counting on a fact that specifying changewave optout applies to all newer changewaves as well and carries forward to the future (so even specifying very old - long long removed - changewave is a way to opt out a new behavior).