[ticket/11890] Fix untranslated string when deleting posts through MCP.

PHPBB3-11890
[ticket/11892] Fix undefined variables: to_forum_id & to_topic_id

PHPBB3-11892
Merge remote-tracking branch 'prototech/ticket/11892' into develop

* prototech/ticket/11892:
  [ticket/11892] Fix undefined variables: to_forum_id & to_topic_id
Merge remote-tracking branch 'prototech/ticket/11890' into develop

* prototech/ticket/11890:
  [ticket/11890] Fix untranslated string when deleting posts through MCP.
[ticket/11898] Correct admin S_LOGIN_ACTION

PHPBB3-11898
[ticket/11898] Correct adm_relative_path created by installer


PHPBB3-11898
Merge remote-tracking branch 'EXreaction/ticket/11898' into develop

* EXreaction/ticket/11898:
  [ticket/11898] Correct adm_relative_path created by installer
  [ticket/11898] Correct admin S_LOGIN_ACTION
Merge remote-tracking branch 'phpbb-core/develop'

* phpbb-core/develop:
  [ticket/11898] Correct adm_relative_path created by installer
  [ticket/11898] Correct admin S_LOGIN_ACTION
  [ticket/11892] Fix undefined variables: to_forum_id & to_topic_id
  [ticket/11890] Fix untranslated string when deleting posts through MCP.