Remove maven-enforcer-plugin plugin

The Maven Enforcer Plugin started to report an internal API
incompatibility after upgrading the build environment to Java 11. Since
the Maven and Java version are guaranteed by the build environment on
Jenkins, there is no urgent need to use this plugin.

Change-Id: Ic8dd4ad322e1b50f4be2750f59fe12c801e1f97c
Signed-off-by: Markus Knauer <mknauer@eclipsesource.com>
diff --git a/releng/org.eclipse.epp.config/parent/pom.xml b/releng/org.eclipse.epp.config/parent/pom.xml
index fc00f02..60e4196 100644
--- a/releng/org.eclipse.epp.config/parent/pom.xml
+++ b/releng/org.eclipse.epp.config/parent/pom.xml
@@ -23,7 +23,6 @@
   <packaging>pom</packaging>
 
   <properties>
-    <java.version>1.8</java.version>
     <maven.version>3.1.1</maven.version>
     <tycho.version>1.2.0</tycho.version>
     <tycho.extras.version>${tycho.version}</tycho.extras.version>
@@ -46,12 +45,6 @@
     <eclipse.simultaneous.release.repository>http://download.eclipse.org/staging/2018-12/</eclipse.simultaneous.release.repository>
   </properties>
 
-  <!--
-     See maven-enforcer-plugin configuration to actually break the build if run with older maven.
-     prerequisites section is kept for now as even if it doesn't break the build, it is used by
-     other plugins like versions-maven-plugin which check and warn for using plugins with older
-     than they require Maven version.
-  -->
   <prerequisites>
     <maven>${maven.version}</maven>
   </prerequisites>
@@ -181,29 +174,6 @@
         </executions>
       </plugin>
 
-      <plugin>
-        <groupId>org.apache.maven.plugins</groupId>
-        <artifactId>maven-enforcer-plugin</artifactId>
-        <executions>
-          <execution>
-            <id>enforce-versions</id>
-            <goals>
-              <goal>enforce</goal>
-            </goals>
-            <configuration>
-              <rules>
-                <requireMavenVersion>
-                  <version>${maven.version}</version>
-                </requireMavenVersion>
-                <requireJavaVersion>
-                  <version>${java.version}</version>
-                </requireJavaVersion>
-              </rules>
-            </configuration>
-          </execution>
-        </executions>
-      </plugin>
-
     </plugins>
 
     <pluginManagement>
@@ -214,11 +184,6 @@
           <version>${tycho.version}</version>
         </plugin>
         <plugin>
-          <groupId>org.apache.maven.plugins</groupId>
-          <artifactId>maven-enforcer-plugin</artifactId>
-          <version>1.4</version>
-        </plugin>
-        <plugin>
           <groupId>org.codehaus.mojo</groupId>
           <artifactId>build-helper-maven-plugin</artifactId>
           <version>1.8</version>