[ticket/11494] Fix memberlist leaders functional tests

The scope of the crawler should be reduced to the specific table

PHPBB3-11494
[ticket/11494] Use functions instead of repeating

PHPBB3-11494
[ticket/11494] Filter crawler in first place

PHPBB3-11494
Merge remote-tracking branch 'nickvergessen/ticket/11494' into develop

* nickvergessen/ticket/11494:
  [ticket/11494] Filter crawler in first place
  [ticket/11494] Use functions instead of repeating
  [ticket/11494] Fix memberlist leaders functional tests