fixes script to migrate comp_tasks table

[sanderegg]

What do these changes do?

• original table was not dropped after migration
  -> was creating issue when deleting projects as the table constrained were still used.

Related issue number

How to test

Checklist

• Did you change any service's API? Then make sure to bundle document and upgrade version (make openapi-specs, git commit ... and then make version-*)
• Unit tests for the changes exist
• Runs in the swarm
• Documentation reflects the changes
• New module? Add your github username to .github/CODEOWNERS

[codecov]

Codecov Report

❗ No coverage uploaded for pull request base (master@6a29b43). Click here to learn what that means.
The diff coverage is n/a.

@@            Coverage Diff            @@
##             master    #1357   +/-   ##
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  Coverage          ?   72.84%           
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  Files             ?      201           
  Lines             ?     8356           
  Branches          ?      937           
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  Hits              ?     6087           
  Misses            ?     1997           
  Partials          ?      272

Flag	Coverage Δ
#integrationtests	57.75% <ø> (?)
#unittests	67.17% <ø> (?)

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