WorkQueue: Fix Coprocess Change Path

[tphung3]

Proposed changes

This fixes issue #3541.

Post-change actions

• make test Run local tests prior to pushing.
• make format Format source code to comply with lint policies. Note that some lint errors can only be resolved manually (e.g., Python)
• make lint Run lint on source code prior to pushing.
• Manual Update Did you update the manual to reflect your changes, if appropriate? This action should be done after your changes are approved but not merged.
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[dthain]

This makes sense to me. I was a little confused at first, until I remembered that WQ coprocesses execute in the workspace directory, and not within their own task directory. (In TV, a serverless library gets its own task directory.)

That said, it looks like there is some lingering problem with TV serverless...