CAMEL-24318 - use Maven parallelization for compilation part of Jbang IT tests on Jenkins

[apupier]

tested with
https://ci-builds.apache.org/job/Camel/job/Camel%20Jbang%20IT%20Tests/job/main/537/

it allows to reduce the part of this build from 1h32min to 37min

Description

Target

• I checked that the commit is targeting the correct branch (Camel 4 uses the main branch)

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• If this is a large change, bug fix, or code improvement, I checked there is a JIRA issue filed for the change (usually before you start working on it).

Apache Camel coding standards and style

• I checked that each commit in the pull request has a meaningful subject line and body.

• I have run mvn clean install -DskipTests locally from root folder and I have committed all auto-generated changes.

AI-assisted contributions

• If this PR includes AI-generated code, commits have proper co-authorship attribution (e.g., Co-authored-by trailers) and the PR description identifies the AI tool used.

[github-actions]

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