[ticket/11336] Changes "leaders"-mode to "team"-mode and so in test-file

PHPBB3-11336
[ticket/11336] Changes language variabel LOGIN_EXPLAIN_LEADERS to _TEAM

PHPBB3-11336
[ticket/11336] Adds redirect for old "leaders" mode

PHPBB3-11336
[ticket/11336] Adds 301 info to redirect

PHPBB3-11336
Merge remote-tracking branch 'crizz0/ticket/11336' into develop-ascraeus

* crizz0/ticket/11336:
  [ticket/11336] Adds 301 info to redirect
  [ticket/11336] Adds redirect for old "leaders" mode
  [ticket/11336] Changes language variabel LOGIN_EXPLAIN_LEADERS to _TEAM
  [ticket/11336] Changes "leaders"-mode to "team"-mode and so in test-file