[Core] Some minor headers clean up

[loumalouomega]

📝 Description

Refactor header guards and improve code structure

• Replaced traditional header guards (#ifndef, #define, #endif) with #pragma once in multiple header files for better portability and ease of maintenance.
• Cleaned up redundant preprocessor directives and ensured consistent header formatting across files.
• Removed unnecessary comments and empty lines.

Files affected:

- amgcl_distributed_csr_spmm_utilities.h
- data_communicator_factory.h
- distributed_model_part_initializer.h
- model_part_communicator_utilities.h
- mpi_normal_calculation_utilities.h

🆕 Changelog

• Some minor headers clean up