[ticket/11528] Move related code from functions_posting to function

Move related code from functions_posting to
remove_post_from_statistic() in content_visibility.php

PHPBB3-11528
[ticket/12738] Inject config object into content_visibility class

PHPBB3-12738
[ticket/12738] Fix tests with new config object injection

PHPBB3-12738
[ticket/12738] Add $config to constructor in notification test

PHPBB3-12738
[ticket/12738] Update constructor docblock

PHPBB3-12738
Merge pull request #2623 from dhruvgoel92/ticket/12738

[ticket/12738] Move related code from functions_posting to function

* dhruvgoel92/ticket/12738:
  [ticket/12738] Update constructor docblock
  [ticket/12738] Add $config to constructor in notification test
  [ticket/12738] Fix tests with new config object injection
  [ticket/12738] Inject config object into content_visibility class
  [ticket/11528] Move related code from functions_posting to function