🔨 Remove unused/unnecessary BCNM code

[claywar]

I affirm:

• [x] I understand that if I do not agree to the following points by completing the checkboxes my issue will be ignored.
• [x] I have read and understood the Contributing Guide and the Code of Conduct.
• [x] I have searched existing issues to see if the issue has already been opened, and I have checked the commit log to see if the issue has been resolved since my server was last updated.

Describe the feature

This is an excerpt from the current wiki involving tasks that should be accomplished after conversion of all existing BCNMs to interaction framework (there may be more, but wanted to track what is done here and leave the guide for others who may be behind)

• [ ] Remove m_RequiredEnemyList from Battlefield
• [x] Remove SpawnLoot
• [x] Remove bcnm_battlefield.sql
• [x] Remove bcnm_treasure_chests.sql
• [x] Remove globals/bcnm.lua
• [ ] Remove xi.battlefield.* lua functions
• [x] Remove bcnm_info usage from CBattlefieldHandler::LoadBattlefield
• [x] Remove CLuaBattlefield::loadMobs
• [ ] Remove Battlefield::getMobs
• [x] Simplify Battlefield::rules (only using loseexp and allowsubjob)
• [ ] Remove BATTLEFIELDMOBCONDITION and just spawn when inserting if set to spawn
• [ ] Cleanup CLuaBaseEntity::registerBattlefield
• [x] Remove ZoneType::BATTLEFIELD_OLD
• [x] Remove CBattlefield::isInteraction()
• [x] Remove xi.battlefield.HandleLootRolls
• [x] Remove xi.battlefield.HandleWipe

[claywar]

Note: CLuaBattlefield::getMobs() is currently used by experimental flag. This could most likely be moved elsewhere.