[fix](class-loader) fix class loader conflict on BE side (#29942)

1. make `hadoop-common` in be java extension as `provided`.
2. must load be java extension jars before hadoop jars

bin/start_be.sh

@@ -89,6 +89,8 @@ if [[ "${MAX_FILE_COUNT}" -lt 60000 ]]; then
 fi
 
 # add java libs
+# Must add hadoop libs, because we should load specified jars
+# instead of jars in hadoop libs, such as avro
 preload_jars=("preload-extensions")
 preload_jars+=("java-udf")
 

fe/be-java-extensions/preload-extensions/pom.xml

@@ -60,6 +60,8 @@ under the License.
         <dependency>
             <groupId>org.apache.hadoop</groupId>
             <artifactId>hadoop-common</artifactId>
+            <!-- Must be provided, we use hadoop_libs in BE's 3rd party instead -->
+            <scope>provided</scope>
         </dependency>
         <dependency>
             <groupId>org.apache.hudi</groupId>