Fix input/output duplication in file_mapper

[lbeckman314]

Important

This PR is built off of PR #1407 and should be merged to it!

TODO: How to do so against forks? Just merge to develop afterwards #1407 is merged?

Overview 🌀

This PR is an initial (un-tested!) pass at resolving the following file_mapper error introduced when merging Commit 5b95fa0:

Error: kubernetes system error (JobCreationFailed):
Failed to create Kubernetes job: Job.batch "<TASK ID>-0" is invalid:
spec.template.spec.containers[0].volumeMounts[2].mountPath: Invalid value: "/data": must be unique

volumeMounts:
  - name: funnel-storage-<TASK ID>
    mountPath: /tmp
    subPath: <TASK ID>/tmp
  - name: funnel-storage-<TASK ID>
    mountPath: /work          <----- Duplicate mountPath ⚠️
    subPath: <TASK ID>/work
  - name: funnel-storage-<TASK ID>
    mountPath: /work          <----- Duplicate mountPath ⚠️
    subPath: <TASK ID>/work
  - name: funnel-storage-<TASK ID>
    mountPath: /local/work/tmp/.../bin
    subPath: <TASK ID>/local/work/tmp/.../bin

volumes:
- name: funnel-storage-<TASK ID>
persistentVolumeClaim:
  claimName: funnel-worker-pvc-<TASK ID>

This duplication is only happening if we have both inputs and outputs (regardless of the number).

Steps to Reproduce

To test it, create any TES task with at least one input and output.

Credit 🤝

This issue was first identified and documented by @nss10 and the CTDS team, thank you!