[ticket/12104] Replace shadow topics $sql with $sql_array for better Event handling

PHPBB3-12104
[ticket/12104] Remove empty LEFT_JOIN array

PHPBB3-12104
[ticket/12104] Remove newline before WHERE parameter

PHPBB3-12104
[ticket/12104] Update the event's doc block to reflect new variable

PHPBB3-12104
Merge pull request #1945 from VSEphpbb/ticket/12104

[ticket/12104] Replace shadow topics $sql with $sql_array for better Eve...