[source_cell] `unitcell.cpp` relies on `source_basis/module_ao/ORB_read.h`

[Critsium-xy]

Describe the Code Quality Issue

Included with the comment "to use 'ORB'", but no ORB / LCAO_Orbitals / Numerical_Orbital symbol is actually used anywhere in the file. This is a dead include and can be deleted with zero risk.

Additional Context

No response

Task list for Issue attackers (only for developers)

• Identify the specific code file or section with the code quality issue.
• Investigate the issue and determine the root cause.
• Research best practices and potential solutions for the identified issue.
• Refactor the code to improve code quality, following the suggested solution.
• Ensure the refactored code adheres to the project's coding standards.
• Test the refactored code to ensure it functions as expected.
• Update any relevant documentation, if necessary.
• Submit a pull request with the refactored code and a description of the changes made.

[Critsium-xy]

This has been solver by #7639