ICU-23054 Fix Eclipse warning, leftover from un-sharing test data

Author: mihnita

icu4j/main/core/pom.xml

@@ -55,29 +55,6 @@
 
   <build>
     <plugins>
-      <plugin>
-        <groupId>org.codehaus.mojo</groupId>
-        <artifactId>build-helper-maven-plugin</artifactId>
-        <executions>
-          <execution>
-            <!-- Test files shared between ICU4C and ICU4J -->
-            <id>add-test-resource</id>
-            <goals>
-              <goal>add-test-resource</goal>
-            </goals>
-            <configuration>
-              <resources>
-                <resource>
-                  <directory>${rootlocation}/../testdata/</directory>
-                  <includes>
-                    <include>message2/**</include>
-                  </includes>
-                </resource>
-              </resources>
-            </configuration>
-          </execution>
-        </executions>
-      </plugin>
       <plugin>
         <groupId>org.apache.maven.plugins</groupId>
         <artifactId>maven-jar-plugin</artifactId>