chore: Adding default value for APPSMITH_CLOUD_SERVICES_TEMPLATE_UPLOAD_AUTH variable (#27354)

## Description
Update sample env files

#### Type of change
- Chore (housekeeping or task changes that don't impact user perception)

## Testing
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#### How Has This Been Tested?
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- [ ] Manual
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- [ ] Cypress
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#### Test Plan
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## Checklist:
#### Dev activity
- [ ] My code follows the style guidelines of this project
- [ ] I have performed a self-review of my own code
- [ ] I have commented my code, particularly in hard-to-understand areas
- [ ] I have made corresponding changes to the documentation
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#### QA activity:
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- [ ] Added `Test Plan Approved` label after JUnit tests were reviewed

app/server/appsmith-server/src/main/resources/application.properties

@@ -80,7 +80,7 @@ appsmith.cloud_services.base_url = ${APPSMITH_CLOUD_SERVICES_BASE_URL:}
 appsmith.cloud_services.signature_base_url = ${APPSMITH_CLOUD_SERVICES_SIGNATURE_BASE_URL:}
 appsmith.cloud_services.username = ${APPSMITH_CLOUD_SERVICES_USERNAME:}
 appsmith.cloud_services.password = ${APPSMITH_CLOUD_SERVICES_PASSWORD:}
-appsmith.cloud_services.template_upload_auth_header = ${APPSMITH_CLOUD_SERVICES_TEMPLATE_UPLOAD_AUTH}
+appsmith.cloud_services.template_upload_auth_header = ${APPSMITH_CLOUD_SERVICES_TEMPLATE_UPLOAD_AUTH:}
 github_repo = ${APPSMITH_GITHUB_REPO:}
 
 # MANDATORY!! No default properties are being provided for encryption password and salt for security.