Remove unused TouchedTarget() methods from examples

[TV4Fun]

Proposed change(s)

Crawler, Walker, and Worm all have TouchedTarget methods to add +1 reward that are, as near as I can tell, completely unused. These are not mentioned anywhere in documentation and are potentially very confusing to someone examining the example code. Remove this methods to make the code cleaner and easier to read.

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

Replacing #5768 so I am not merging from my main branch.

Types of change(s)

• [ ] Bug fix
• [ ] New feature
• [x] 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