allow service-tests to run without var

[michel-laterman]

Builds on main are failing due to pipeline.service-tests.yml having an undefined variable.
Allow service tests to run without $ENVIRONMENT variable being defined.

[elasticmachine]

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• Start Time: 2023-07-31T16:11:56.464+0000

• Duration: 36 min 4 sec

Test stats 🧪

Test	Results
Failed	0
Passed	755
Skipped	1
Total	756

💚 Flaky test report

Tests succeeded.

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