Retry COS requests & other tweaks

[LachlanStuart]

These are changes I've made locally to get benchmarks to run.

• Most COS requests during and after the annotate step will now retry. I've consolidated the logic into utils and made sure that exceptions are always logged, and rethrown if there's a repeated failure.
  • Also, many requests now pass the stream to msgpack.load instead of downloading the entire object to a buffer before converting it. In theory this could save some memory, but I haven't tested if that's actually the case.
• The cpyMSpec version has been pinned to 0.3.5. This is needed for the tests in Experiment 1 to pass. I've also added an assertion to isocalc_wrapper.py to ensure that the correct version is used, because it's otherwise very difficult to debug why the test is failing.
• Experiment 3 has been changed to use the "huge3" dataset

[LachlanStuart]

@omerb01 I've replaced the other uses of get_object. Re-ran the pipeline on "big" to test and it worked.