Clean-up repo from old unused files/directories.

..._tools/HPC_scripts_prior/data_extraction_era5_template.sh

...tools/HPC_scripts_prior/meta_postprocess_era5_template.sh

.../HPC_scripts_prior/preprocess_data_era5_step1_template.sh

.../HPC_scripts_prior/preprocess_data_era5_step2_template.sh

...tion_tools/HPC_scripts_prior/train_model_era5_template.sh

.../HPC_scripts_prior/visualize_postprocess_era5_template.sh

video_prediction_tools/env_setup/create_env_non_HPC.sh