Revert "Skip tests completely while building PMD"

We need to compile tests, as pmd-ant is depending on the test artifacts from pmd-core...

This reverts commit 9cb700b.

Author: adangel

lib/pmdtester/builders/pmd_report_builder.rb

@@ -256,7 +256,7 @@ def build_pmd_with_maven
                       # build command since PMD migrated to central portal
                       './mvnw clean package -V ' \
                         '-PfastSkip ' \
-                        '-Dmaven.test.skip=true ' \
+                        '-DskipTests ' \
                         '-T1C -B'
                     else
                       extra_java_home = "#{Dir.home}/openjdk11"

test/test_pmd_report_builder.rb

@@ -388,7 +388,7 @@ def stub_pmd_build_maven_new_pmd7_build
     PmdTester::Cmd.stubs(:execute_successfully).with do |cmd, extra_java_home|
       if cmd == './mvnw clean package -V ' \
                 '-PfastSkip ' \
-                '-Dmaven.test.skip=true ' \
+                '-DskipTests ' \
                 '-T1C -B' &&
          extra_java_home.nil?
         FileUtils.mkdir_p 'pmd-dist/target'