[ticket/11963] Don't depend on user_notify flag to delete report notifications.

PHPBB3-11963
[ticket/11963] Delete topic_in_queue notifications in MCP approve_details mode

PHPBB3-11963
[ticket/11963] Fix undefined variable: post_data when mass-approving topics.

PHPBB3-11963
Merge pull request #1889 from prototech/ticket/11963

[ticket/11963] Remove stale MCP notifications.