[ticket/12174] Update topic_attachment flag when a post is soft-deleted

https://tracker.phpbb.com/browse/PHPBB3-12174

PHPBB3-12174
[ticket/12174] Corrections

PHPBB3-12174
[ticket/12174] Revert the changes on $topic_update_array

PHPBB3-12174
[ticket/12174] Update sql query

PHPBB3-12174
[ticket/12174] Remove inline assignment

PHPBB3-12174
[ticket/12174] Update the conditions

PHPBB3-12174
[ticket/12174] Don't update the flag for a post without attachment

PHPBB3-12174
[ticket/12174] Remove $update_topic_attachments_flag

PHPBB3-12174
[ticket/12174] Coding style

PHPBB3-12174
[ticket/12174] Add tests

PHPBB3-12174
Merge pull request #2426 from Nicofuma/ticket/12174

[ticket/12174] Update topic_attachment flag when a post is soft-deleted

* Nicofuma/ticket/12174:
  [ticket/12174] Add tests
  [ticket/12174] Coding style
  [ticket/12174] Remove $update_topic_attachments_flag
  [ticket/12174] Don't update the flag for a post without attachment
  [ticket/12174] Update the conditions
  [ticket/12174] Remove inline assignment
  [ticket/12174] Update sql query
  [ticket/12174] Revert the changes on $topic_update_array
  [ticket/12174] Corrections
  [ticket/12174] Update topic_attachment flag when a post is soft-deleted