[SPARK-3974] Remove setPartition method. Isn't required

Author: brkyvz

mllib/src/main/scala/org/apache/spark/mllib/linalg/distributed/BlockMatrix.scala

@@ -106,7 +106,7 @@ class BlockMatrix(
     this(numRowBlocks, numColBlocks, rdd)
     val part = new GridPartitioner(numRowBlocks, numColBlocks, rowsPerBlock,
       colsPerBlock, rdd.partitions.length)
-    setPartitioner(part)
+    partitioner = part
   }
 
   private[mllib] var partitioner: GridPartitioner = {
@@ -115,14 +115,6 @@ class BlockMatrix(
       firstSubMatrix.numRows, firstSubMatrix.numCols, rdd.partitions.length)
   }
 
-  /**
-   * Set the partitioner for the matrix. For internal use only. Users should use `repartition`.
-   * @param part A partitioner that specifies how SubMatrices are stored in the cluster
-   */
-  private def setPartitioner(part: GridPartitioner): Unit = {
-    partitioner = part
-  }
-
   private lazy val dims: (Long, Long) = getDim
 
   override def numRows(): Long = dims._1