Upload oslo.messaging final releases to pypi

In I87eaefb37fa52142d47b4aba4f3f76452771f74e, we enabled uploading
oslo.messaging beta releases to pypi understanding that we would
disable this behaviour once we had a final release of oslo.messaging.

Now that we're ready to release oslo.messaging 1.3.0, re-enable
uploading final releases and disable uploading beta releases.

The plan for beta releases in Juno is still that we will do wheel-only
uploads.

Change-Id: I99bcede6988cf3263e82b4b13b8a5253b7fdbbd5
Merge "Upload oslo.messaging final releases to pypi"