[HUDI-3743] Support DELETE_PARTITION for metadata table (#5169)

In order to drop any metadata partition (index), we can reuse the DELETE_PARTITION operation in metadata table. Subsequent to this, we can support drop index (with table config update) for async metadata indexer.

- Add a new API in HoodieTableMetadataWriter
- Current only supported for Spark metadata writer

hudi-client/hudi-flink-client/src/main/java/org/apache/hudi/metadata/FlinkHoodieBackedTableMetadataWriter.java

@@ -31,6 +31,7 @@ import org.apache.hudi.common.util.Option;
 import org.apache.hudi.common.util.ValidationUtils;
 import org.apache.hudi.config.HoodieWriteConfig;
 import org.apache.hudi.exception.HoodieMetadataException;
+import org.apache.hudi.exception.HoodieNotSupportedException;
 
 import org.apache.avro.specific.SpecificRecordBase;
 import org.apache.hadoop.conf.Configuration;
@@ -161,4 +162,9 @@ public class FlinkHoodieBackedTableMetadataWriter extends HoodieBackedTableMetad
     // Update total size of the metadata and count of base/log files
     metrics.ifPresent(m -> m.updateSizeMetrics(metadataMetaClient, metadata));
   }
+
+  @Override
+  public void deletePartitions(String instantTime, List<MetadataPartitionType> partitions) {
+    throw new HoodieNotSupportedException("Dropping metadata index not supported for Flink metadata table yet.");
+  }
 }