Fix the migration adding the contest data to moves by removing a wrongly named file

[Aelysya]

Description

This PR adds a line to the migration that adds the contest data to moves.
This was done to prevent a known issue with the Gen 9 datapack that contains a file named differently from the db_symbol it contains, effectively duplicating it during the migration and causing the project to not be able to load due to the old file not being compliant with the Zod format.

Closes #650

Note before testing

In a pre-2.7.0 project, create a file named kotow_cleave in your moves folder. Paste this content inside:

{
  "klass": "Move",
  "id": 902,
  "dbSymbol": "kowtow_cleave",
  "mapUse": 0,
  "battleEngineMethod": "s_basic",
  "type": "dark",
  "power": 85,
  "accuracy": 0,
  "pp": 10,
  "category": "physical",
  "movecriticalRate": 1,
  "priority": 0,
  "isAuthentic": false,
  "isBallistics": false,
  "isBite": false,
  "isBlocable": true,
  "isCharge": false,
  "isDance": false,
  "isDirect": true,
  "isEffectChance": false,
  "isGravity": false,
  "isHeal": false,
  "isKingRockUtility": true,
  "isMagicCoatAffected": false,
  "isMental": false,
  "isMirrorMove": true,
  "isNonSkyBattle": false,
  "isPowder": false,
  "isPulse": false,
  "isPunch": false,
  "isRecharge": false,
  "isSnatchable": false,
  "isSoundAttack": false,
  "isSlicingAttack": true,
  "isUnfreeze": false,
  "isWind": false,
  "battleEngineAimedTarget": "adjacent_pokemon",
  "battleStageMod": [],
  "moveStatus": [],
  "effectChance": 0,
}

• Note the difference between the db_symbol and the file name (kotow/kowtow)

Tests to perform

• Try loading the project, the migration should work and the project should load
• The old file named kotow_cleave.json has been removed
• The new file named kowtow_cleave.json has been correctly created
• Launching the migration on a project that does not contain this file works correctly