Add Elasticsearch tests

Relates #131 (closed)

MR adds refactored Search tests that target Advanced Search now that Elasticsearch is being enabled on the environments.

• Adds in Search tests for Advanced Search that cover the 3 available levels - Global, Groups and Projects - with environment config
• New check function added for k6 tests to check if an environment has a specific setting set via the Settings API.
• New debug environment variable to add a sleep between test runs
• General tweaks and improvements