Change the default fields (columns) in contact search results
There is a non-code fix for this:

You could make a profile with the fields you want to display.

And then you search using Advanced Search, and you could select that profile in the "display result as".

Edit:
As pointed out by Philipp Michael in the comments below, you could also choose a certain profile as the default one, in the admin settings ( at /civicrm/admin/setting/search?reset=1.)