fix(ingest/tableau): Fix TableauUpstream create check

[treff7es]

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

All modified and coverable lines are covered by tests ✅

Files with missing lines	Coverage Δ
...on/src/datahub/ingestion/source/tableau/tableau.py	88.61% <ø> (ø)
...datahub/ingestion/source/tableau/tableau_common.py	91.62% <ø> (-0.05%)	⬇️

... and 1508 files with indirect coverage changes

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