CLN/DOC: standardize wording on previous-removals
In the 1.0.0 whatsnew we currently have 3 variants of "Removed :foo:X"

```
- Removed the previously deprecated :meth:`X`
- Removed previously deprecated :meth:`X`
- Removed :meth:`X`
```

I think we should standardize on one of these (lest readers think the difference is meaningful).  I don't particularly care which, but for this PR went with the last one as it is the least verbose
The next step in this process would be to standardize wording for "removed keyword X from Y" thanks