chore: fix syntax error in_docker variable (#41041)

## Description
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extremely technical (helps the content, marketing, and DevRel team)._
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> _Please also include relevant motivation and context. List any
dependencies that are required for this change. Add links to Notion,
Figma or any other documents that might be relevant to the PR._


Fixes #`Issue Number`  
_or_  
Fixes `Issue URL`
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> _If no issue exists, please create an issue first, and check with the
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## Automation

/ok-to-test tags=""

### 🔍 Cypress test results
<!-- This is an auto-generated comment: Cypress test results  -->
> [!WARNING]
> Tests have not run on the HEAD
48aa44719e39cd7999251222edd7a594ab2e612f yet
> <hr>Wed, 25 Jun 2025 13:11:28 UTC
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## Communication
Should the DevRel and Marketing teams inform users about this change?
- [ ] Yes
- [ ] No


<!-- This is an auto-generated comment: release notes by coderabbit.ai
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## Summary by CodeRabbit

- **Bug Fixes**
- Corrected formatting and quoting issues in the deployment script to
ensure proper environment variable expansion and configuration output.

<!-- end of auto-generated comment: release notes by coderabbit.ai -->

scripts/deploy_preview.sh

@@ -15,7 +15,7 @@ export cluster_name=uatx-cluster
 
 echo "[default]
 region = $region
-output = json
+output = json"
 
 echo "Region: $region"
 echo "Cluster name: $cluster_name"
@@ -105,6 +105,6 @@ helm upgrade -i "$CHARTNAME" "appsmith-ee/$HELMCHART" -n "$NAMESPACE" --create-n
   --set applicationConfig.APPSMITH_CARBON_API_KEY="$APPSMITH_CARBON_API_KEY" \
   --set applicationConfig.APPSMITH_CARBON_API_BASE_PATH="$APPSMITH_CARBON_API_BASE_PATH" \
   --set applicationConfig.APPSMITH_AI_SERVER_MANAGED_HOSTING="$APPSMITH_AI_SERVER_MANAGED_HOSTING" \
-  --set applicationConfig.IN_DOCKER='$IN_DOCKER' \
+  --set applicationConfig.IN_DOCKER="$IN_DOCKER" \
   --set applicationConfig.APPSMITH_CUSTOMER_PORTAL_URL="https://release-customer.appsmith.com" \
   -f dp-node-affinity-values.yaml