This change fixes the step mavenExecuteStaticCodeChecks to skip execution
if no tool is configured. Previously, the step was executed even when both
supported tools, i.e., PMD and SpotBugs were disabled.
Also establish mavenExecute() via new JenkinsMavenExecuteRule in Groovy Unit Tests.
Co-authored-by: Stephan Aßmus <stephan.assmus@sap.com>
Co-authored-by: Christopher Fenner <26137398+CCFenner@users.noreply.github.com>