Replace some uses of deprecated wfFindFile() and wfLocalFile()

Replace some uses of deprecated wfFindFile() and wfLocalFile()

These global functions were deprecated in 1.34 and services made
available to replace them. See services below;

* wfFindFile() - MediaWikiServices::getInstance()->getRepoGroup()->findFile()
* wfLocalFind() - MediaWikiServices::getInstance()->getRepoGroup()->getLocalRepo()->newFile()

NOTES:

* wfFindFile() and wfLocalFind() usages in tests have been ignored
  in this change per @Timo's comments about state of objects.

* includes/upload/UploadBase.php also maintained for now as it causes
  some failures I don't fully understand, will investigate and handle
  it in a follow up patch.

* Also, includes/MovePage.php

Change-Id: I9437494de003f40fbe591321da7b42d16bb732d6