Cost reduction CSV has unnecessary technology_type column

[measrainsey]

Within the cost_reduction.csv files in the costs tool, there is a column called technology_type that isn't used anywhere (in fact the only times the column is referenced in the code base is to be deleted from a dataframe). This is carried over from the legacy costs work/Excel spreadsheet, and I didn't remove it when building the current costs tool. Making a note for myself to just create a PR to remove this column in the input CSVs and remove references to it in the code.