Remove jacoco from pom.xml

[wing328]

To fix #6443. A user has confirmed it's fixed locally in his machine with this fix.

cc @OpenAPITools/generator-core-team

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[jimschubert]

Can we put this under a profile instead? This will cause us to lose coverage details in Sonar.

[jimschubert]

Another option would be for us to set -Djacoco.skip=true in the docker script.

[wing328]

Done.