Migration: Remove %CheckEncodingColumns

[bschmalhofer]

While looking into this I noticed that in Kernel/System/MigrateFromOTRS/CloneDB/Backend.pm the following hash is set up:

    my %CheckEncodingColumns = (
        'article_data_mime.a_body'              => 1,
        'article_data_mime_attachment.filename' => 1,
    );

It looks like this setup has no effect at all. Should be tidied in rel-10_1.

Originally posted by @bschmalhofer in #1296 (comment)

[bschmalhofer]

A test mgration looked fine. The PR is merged. Closing this issue.