Remove EndEpisode from the dungeon env. (Conflicts with docs)

[andrewcoh]

Proposed change(s)

EndEpisode has no effect here but conflicts with our documentation https://github.com/Unity-Technologies/ml-agents/blob/main/docs/Learning-Environment-Design-Agents.md#cooperative-behaviors-notes-and-best-practices

Useful links (Github issues, JIRA tickets, ML-Agents forum threads etc.)

Types of change(s)

• Bug fix
• New feature
• Code refactor
• Breaking change
• Documentation update
• Other (please describe)

Checklist

• Added tests that prove my fix is effective or that my feature works
• Updated the changelog (if applicable)
• Updated the documentation (if applicable)
• Updated the migration guide (if applicable)

Other comments