(bug 44629) Clean up $wgMetaNamespace, $wgMetaNamespaceTalk

This patch removes unneccessary entries for $wgMetaNamespace
and $wgMetaNamespaceTalk per bug 44629.

Some $wgMetaNamespace entries are already defined per-family
at the top of that "section", and $wgMetaNamespaceTalk
definitions are already available globally in appropriate l10n
files in core, such as MessagesBa.php, MessagesBr.php and
MessagesEs.php, to take the first three examples.

I'm also using this opportunity to clean up some weird spacing
and indentation.

See bug 29902 for other things that might require cleaning up.

Bug: 44629
Change-Id: Id26203fcb2e5e95325dc374dad222f0d68a67f17