Move the repository size from the Settings page back to the Overview page. (BB-11462)

In a comment discussion about the obscurely placed repository size (cf. starting here Re: What kind of limits do you have on repository/file/upload size?), Marcus Bertrand [Atlassian] has two comments about the fact that the repository size "previously was on the repository overview" – a very logical and accessible location. As he and Erik van Zijst [Atlassian] explained, it was subsequently moved to its present (non-obvious and not always accessible) location.

Besides being a non-obvious location (i.e. no one sets the repository size as one sets other settings on the Settings page), putting it into the Settings also creates access problems for those who do not have permission to change Settings. This was discovered and pointed out by Christopher Corbell (cf. comments starting here Re: Reduce repository size).

Moving repository size back into the repository overview – where everyone can easily find it and all are allowed to see it – would be a very good fix from the earlier change that created these problems.