Make test providers static

This changeset changes the providers and some additional calls to
use what is said to be the preferred form.

According to Krinkle the test providers should be static
(https://gerrit.wikimedia.org/r/#/c/34524/1/repo/tests/phpunit/includes/FuzzyCompareTest.php)
and core has converted to this. That said the test infact work and
gives the correct result when the providers are non-static. This is
also according to the manual for PHPunit which uses both forms.

My opinion is that static is unnecessary by example, but if the
change makes people happy, then why not.

Change-Id: I1576115caf6d14524289e406df205e6f91b6f8f4
Merge "Make test providers static"