The use of "-Dsonar.dynamicAnalysis=false" standard parameter should deactivate the execution of PHP_Unit

Each sub plugin of the sonar php plugin can be disactived by adding the corresponding property:
<sonar.phpUnit.shouldRun>false</sonar.phpUnit.shouldRun>
<sonar.phpPmd.shouldRun>false</sonar.phpPmd.shouldRun>
<sonar.phpCodesniffer.shouldRun>false</sonar.phpCodesniffer.shouldRun>
<sonar.phpDepend.shouldRun>false</sonar.phpDepend.shouldRun>

Sonar documentation says:
Dynamic analysis relates to unit tests execution. By default, those unit tests are executed but you can optionally decide to do only static analysis or to reuse existing unit tests reports.

is it really supposed to disactivate the unit tests plugin?
or should it have to make the phpunit use existing phpunit.xml file if exist ?

Yes standard property sonar.dynamicAnalysis is supposed to desactivate execution of the phpunit plugin

Enable static anaylisis if analyze only is set to true or dynamic analysis is set to false