Rename release branch to release-2.XX instead of release-2.XX.0

[damccorm]

This makes more sense because it allows us to cut patch releases off the same branch. This is also convenient because it allows us to cherry-pick low risk, moderate value fixes to the release branch in case a patch happens, and it is just all around a more accurate naming.

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[damccorm]

This is ready to go, but I will hold it until the current release completes to avoid breaking things for that release.