Consider not expiring new builds within the same version on TestFlight

[kitallis]

We currently expire the previous build if a new build is added for the same version on TestFlight. This is because TF does not allow sending the new build for review if the previous one is already in review.

We originally did this because it was a simple enough solution. But this becomes a problem when two steps send builds for the same version in quick succession, for eg. during a hotfix, the previous build can easily get expired.