L2 flow fixes

[eelcovdw]

Description

Various fixes for L2 deposit_result flow

Fixes:

• Calling deposit_result on L2 request throws exception when input policy contains constants
• ds_client.code.my_func(blocking=False) starts a job that never finishes
  • new behaviour: job is started and errors because: not approved.
  • This is a quickfix. open issue: https://github.com/OpenMined/Heartbeat/issues/1750
• Custom API endpoint job that errors never finishes
  • Same as previous item
• usercode repr exception when input policy contains constants.
  • new behaviour:

Not fixed:

• when DS runs custom endpoint with blocking=False, a new job is created instead of retrieving existing job from cache
• New job.result contains unexpected datastructure with CachedSyftObject
  • To get result, have to call job.result.result

Affected Dependencies

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How has this been tested?

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Checklist

• [ ] I have followed the Contribution Guidelines and Code of Conduct
• [ ] I have commented my code following the OpenMined Styleguide
• [ ] I have labeled this PR with the relevant Type labels
• [ ] My changes are covered by tests