BYOC: small fixes to job_rpc after refactor

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What does this pull request do? Explain your changes. (required)

• Small fixes to job_rpc refactor with route forward handling in submitJob
• add nil check to job_stream send to worker that is not responding
  • does not crash node but has a nil error when body is nil.
    Specific updates (required)

How did you test each of these updates (required)

Built docker locally and ran end to end. Added test for job_rpc submitJob to confirm request to Orch is as expected.

Does this pull request close any open issues?

Checklist:

• Read the contribution guide
• make runs successfully
• All tests in ./test.sh pass
• README and other documentation updated
• Pending changelog updated

[codecov]

Codecov Report

❌ Patch coverage is 0% with 8 lines in your changes missing coverage. Please review.
✅ Project coverage is 33.13373%. Comparing base (88807fa) to head (d955771).

Files with missing lines	Patch %	Lines
server/job_stream.go	0.00000%	8 Missing ⚠️

Additional details and impacted files

@@                 Coverage Diff                 @@
##              master       #3803         +/-   ##
===================================================
+ Coverage   33.05093%   33.13373%   +0.08280%     
===================================================
  Files            160         160                 
  Lines          40250       40246          -4     
===================================================
+ Hits           13303       13335         +32     
+ Misses         25904       25861         -43     
- Partials        1043        1050          +7     

Files with missing lines	Coverage Δ
server/job_rpc.go	49.22680% <ø> (+4.34189%)	⬆️
server/job_stream.go	55.72034% <0.00000%> (+0.20017%)	⬆️

... and 2 files with indirect coverage changes

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Files with missing lines	Coverage Δ
server/job_rpc.go	49.22680% <ø> (+4.34189%)	⬆️
server/job_stream.go	55.72034% <0.00000%> (+0.20017%)	⬆️

... and 2 files with indirect coverage changes

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FYI this is not relevant with #3727 being reverted