explicit execution for maven-surefire-plugin with Tycho 4

Due to changes in Tycho 4: the test mojo of the maven-surefire-plugin is
no longer part of the default life-cycle

pom.xml

@@ -521,8 +521,9 @@
 					<artifactId>maven-surefire-plugin</artifactId>
 					<version>${maven-surefire-version}</version>
 					<!--
-					This is not needed now, but will be needed when switching to Tycho 4.0.0
+					This is needed due to changes in Tycho 4.0.0
 					see https://github.com/eclipse-tycho/tycho/blob/master/RELEASE_NOTES.md#using-integrationplugin-tests-with-eclipse-plugin-packaging
+					-->
 					<executions>
 						<execution>
 							<id>execute-unit-tests</id>
@@ -531,7 +532,6 @@
 							</goals>
 						</execution>
 					</executions>
-					-->
 					<configuration>
 						<!--
 						The Surefire Plugin excludes nested classes by default: http://maven.apache.org/surefire/maven-surefire-plugin/test-mojo.html#excludes