ci: ability to skip elasticsearch in integration tests

[hamza-m-masood]

Which problem does the PR fix?

In this PR, I am attempting to add configuration to the integration tests to have the ability to skip elasticsearch.
related issue: #2626

What's in this PR?

Checklist

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[hamza-m-masood]

I found out from the build from this commit that the charts/camunda-platform-8.6/test/integration/testsuites/vars/files/variables.env is read from the main branch