bugfix: pipeline without computational service is not created in comp_tasks table

[sanderegg]

Fixes issue where Mattward/Jupyters e2e was failing.
When there are no computational services in a pipeline, the entries shall still be made in comp_tasks table for the dynamic services to run correctly.

What do these changes do?

Related issue/s

How to test

make build-x up-prod

create a pipeline with just dynamic services... retrieve data is working as it should.

Checklist

[codecov]

Codecov Report

Merging #2105 (783e70b) into master (8501538) will increase coverage by 0.0%.
The diff coverage is 100.0%.

@@          Coverage Diff           @@
##           master   #2105   +/-   ##
======================================
  Coverage    73.7%   73.7%           
======================================
  Files         454     454           
  Lines       16777   16777           
  Branches     1668    1668           
======================================
+ Hits        12371   12377    +6     
+ Misses       3957    3954    -3     
+ Partials      449     446    -3     

Flag	Coverage Δ
integrationtests	65.4% <100.0%> (+<0.1%)	⬆️
unittests	67.3% <0.0%> (-0.1%)	⬇️

Flags with carried forward coverage won't be shown. Click here to find out more.

Impacted Files	Coverage Δ
...ore_service_director_v2/api/routes/computations.py	89.1% <100.0%> (ø)
...simcore_service_webserver/projects/projects_api.py	85.0% <0.0%> (+0.5%)	⬆️
...ce_webserver/resource_manager/garbage_collector.py	78.5% <0.0%> (+0.9%)	⬆️
...webserver/computation_comp_tasks_listening_task.py	91.0% <0.0%> (+3.3%)	⬆️

[GitHK]

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