feat(ingest/datahub): use a CTE instead of subqueries

[hsheth2]

Checklist

• The PR conforms to DataHub's Contributing Guideline (particularly Commit Message Format)
• Links to related issues (if applicable)
• Tests for the changes have been added/updated (if applicable)
• Docs related to the changes have been added/updated (if applicable). If a new feature has been added a Usage Guide has been added for the same.
• For any breaking change/potential downtime/deprecation/big changes an entry has been made in Updating DataHub

[codecov]

Codecov Report

Attention: Patch coverage is 0% with 4 lines in your changes missing coverage. Please review.

✅ All tests successful. No failed tests found.

Files with missing lines	Patch %	Lines
...ngestion/source/datahub/datahub_database_reader.py	0.00%	4 Missing ⚠️

Files with missing lines	Coverage Δ
...ngestion/source/datahub/datahub_database_reader.py	56.43% <0.00%> (-1.15%)	⬇️

... and 1 file with indirect coverage changes

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