Tests fail confusingly without XDS

Running tests _without_ XDS present give:
```
for step in ["XYCORR", "INIT", "COLSPOT", "IDXREF"]:
> lastrecord = open("%s.LP" % step).readlines()[-1]
E FileNotFoundError: [Errno 2] No such file or directory: 'XYCORR.LP'

fast_dp/autoindex.py:106: FileNotFoundError
```
This is because `run_job` [doesn't check and provides no way to tell if the process actually ran](https://github.com/DiamondLightSource/fast_dp/blob/4ea4775955826230f92e4246c6cccc4df87ef8b7/fast_dp/run_job.py#L7), so autoindex just carries on as if it's worked:
https://github.com/DiamondLightSource/fast_dp/blob/4ea4775955826230f92e4246c6cccc4df87ef8b7/fast_dp/autoindex.py#L98