[datatables] numeric sorting only working on purge when page cache is set

[krabina]

Issue

when $wgCachePages is set to true and numeric sorting is set, Then the datatables sorting always ignores the collation setting (numeric) and datatables are sorted wrongly (in the default collation). When you click "purge page", the sorting is in order once, but on a page reload, the wrong sorting order is showing up.

Expected result: Order of pages in datatables should always consider collation settings.

[krabina]

PR coming up soon :-)

[krabina]

Probably related to #571