Backport PR #15535 to 8.11: Fixed functional test in case the LS_JAVA_HOME is configured

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Backport PR #15535 to 8.11 branch, original message:

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Release notes

[rn:skip]

What does this PR do?

Adds filtering on Logstash output message in an integration tests when setting LS_JAVA_HOME environment variable.

Why is it important/What is the impact to the user?

As a developer I want to run integration tests customizing the JDK and not using the bundled one.

Checklist

• My code follows the style guidelines of this project
• [ ] I have commented my code, particularly in hard-to-understand areas
• [ ] I have made corresponding changes to the documentation
• [ ] I have made corresponding change to the default configuration files (and/or docker env variables)
• I have added tests that prove my fix is effective or that my feature works

Author's Checklist

• [ ]

How to test this PR locally

export LS_JAVA_HOME=/path/to/JDK
./gradlew runIntegrationTests -PrubyIntegrationSpecs="specs/command_line_spec.rb"

Related issues

• Closes IT tests (part 1) failing when using a custom Java with LS_JAVA_HOME #15529

Use cases

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Logs

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cc @andsel