[ticket/11615] Rename init_test to creation_test for clarity

PHPBB3-11615
[ticket/11615] Rename class in file to match

PHPBB3-11615
[ticket/11615] Remove magic number in creation_test

Removing this magic number to its own variable
with clean multiplication makes it clear
what the number represents.

PHPBB3-11615
[ticket/11615] Fix typo in creation_test

PHPBB3-11615
Merge remote-tracking branch 'asperous/ticket/11615/creation_test' into develop-olympus

* asperous/ticket/11615/creation_test:
  [ticket/11615] Fix typo in creation_test
  [ticket/11615] Remove magic number in creation_test
  [ticket/11615] Rename class in file to match
  [ticket/11615] Rename init_test to creation_test for clarity