[ticket/12503] All tests should extend \phpbb_test_case

PHPBB3-12503
[ticket/12486] Rename data provider to fix "Risky" from phpunit

PHPBB3-12486
[ticket/12486] Make assertion on the return to remove "Risky" from phpunit

PHPBB3-12486
[ticket/12504] Remove unused request object from avatar manager test

PHPBB3-12504
[ticket/12504] Use defined variables

PHPBB3-12504
[ticket/12504] Use local variables where possible

PHPBB3-12504
Merge pull request #2411 from nickvergessen/ticket/12503

[ticket/12503] Fix several errors in test suite