Add pluginManagement section for storage-targets/cds-feature-attachments-oss

[lisajulia]

Try to fix the failing maven deployment https://github.com/cap-java/cds-feature-attachments/actions/runs/17241063009/job/48918884538 with this, because the error is:

Deployment failed
pkg:maven/com.sap.cds/[email protected]:

• Sources must be provided but not found in entries
• Javadocs must be provided but not found in entries

[BraunMatthias]

Try to add a section like

  <plugin>
                <artifactId>maven-javadoc-plugin</artifactId>
                <configuration>
                    <failOnError>true</failOnError>
                    <doclint>all,-missing</doclint>
                </configuration>
                <executions>
                    <execution>
                        <goals>
                            <goal>jar</goal>
                        </goals>
                        <configuration>
                            <excludePackageNames>${generation-package}.*</excludePackageNames>
                        </configuration>
                    </execution>
                </executions>
            </plugin>

            <plugin>
                <artifactId>maven-source-plugin</artifactId>
                <executions>
                    <execution>
                        <goals>
                            <goal>jar</goal>
                        </goals>
                    </execution>
                </executions>
            </plugin>
        </plugins>

to the srv pom.xml like here.

[lisajulia]

@BraunMatthias: Can you have another look? Thanks!