[JENKINS-51247] Always use source:jar, not source:jar-no-fork.

pom.xml

@@ -733,6 +733,34 @@
        <maven.repository.update.freqency>always</maven.repository.update.freqency>
      </properties>
    </profile>
    <profile> <!-- JENKINS-51247: bypass MNG-6405 by avoiding use of forked executions incl. from source:jar -->
      <id>fix-superpom-source-fork</id>
      <activation>
        <property>
          <name>performRelease</name>
          <value>true</value>
        </property>
      </activation>
      <build>
        <plugins>
          <plugin>
            <artifactId>maven-source-plugin</artifactId>
            <executions>
              <execution>
                <id>attach-sources</id>
                <phase>DO-NOT-ACTUALLY-RUN</phase>
              </execution>
              <execution>
                <id>attach-sources-no-fork</id>
                <goals>
                  <goal>jar-no-fork</goal>
                </goals>
              </execution>
            </executions>
          </plugin>
        </plugins>
      </build>
    </profile>
    <profile> <!-- see JEP-305 -->
      <id>consume-incrementals</id>
      <repositories>