remove ObservationPoints script

[SarahAlidoost]

Description

closes #101 . I tested this branch with three site data. The results are the same as those generated by the main branch.

Checklist

• [x] Add a reference to related issues.
• [x] @mentions of the person or team responsible for reviewing proposed changes.
• [x] This pull request has a descriptive title.
• [x] Code is written according to the guidelines.
• [x] The checks by MISS_HIT style checker and linter, below the pull request, are successful (green).
• [x] Documentation is available.
• [x] Add changes to the changelog file under section Unreleased.
• [x] Model runs successfully.
• [x] Ask a meinatainer to re-generate exe file if matlab codes are changed. About how to create an exe file, see exe readme.