fix(elastic-setup) Fixing env var logic

[pedro93]

Fixes #6060, tested locally by reproducing issue with Quickstart, building the updated image and deploying it using quickstart.

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

[github-actions]

Unit Test Results (build & test)

584 tests  ±0   580 ✔️ ±0   12m 49s ⏱️ - 1m 9s
143 suites ±0       4 💤 ±0 
143 files   ±0       0 ❌ ±0 

Results for commit c0e8ec1. ± Comparison against base commit 09dec1a.

[anshbansal]

LGTM