Draft: [RTA/DPA BW tests]: A few simplifications

Laying foundations for a sprucing pass and TurCal sprucing job in the sprucing bandwidth tests.

• Simplify the generation and download of the on-the-fly sprucing config yaml files. (sorts out this discussion in #13)
• Put the list of lines for TISTOS in the on-the-fly config file. Now need to only generate and download 1 file.
• Remove nested Gaudi job that works out the rate denominator. Now we have a second job, after the main trigger job, that explicitly does that and only that.
• Rename generate_hlt2_fullstream_metadata.py -> generate_spruce_input_configs.py to make use case more clear.
• Introduce a tmp/to_eos/ directory into which we put everything that the handler needs to grab and put under current_hlt2_output on eos. This means we don't need to align paths here and in the handler.
• Trim down the list of helper functions,
• Remove a load of fancy stuff in run_bandwidth_test_jobs that no-one has run since Ella left,

TODO:

• Put tuples to be copied into to_eos/ and just grab from there