Increase perfomance of BulkAppend and BulkFlush (#14067)
Increase perfomance of BulkAppend and BulkFlush (#14067)

* Better bulkappend

* Fix lint

ForkedReposBak/mxnet,ForkedReposBak/mxnet,larroy/mxnet,yajiedesign/mxnet,yajiedesign/mxnet,szha/mxnet,sxjscience/mxnet,zhreshold/mxnet,DickJC123/mxnet,apache/incubator-mxnet,leezu/mxnet,reminisce/mxnet,ForkedReposBak/mxnet,tlby/mxnet,leezu/mxnet,reminisce/mxnet,reminisce/mxnet,leezu/mxnet,tlby/mxnet,DickJC123/mxnet,dmlc/mxnet,apache/incubator-mxnet,sxjscience/mxnet,sxjscience/mxnet,zhreshold/mxnet,tlby/mxnet,dmlc/mxnet,dmlc/mxnet,yajiedesign/mxnet,apache/incubator-mxnet,dmlc/mxnet,tlby/mxnet,dmlc/mxnet,leezu/mxnet,larroy/mxnet,szha/mxnet,szha/mxnet,ForkedReposBak/mxnet,larroy/mxnet,zhreshold/mxnet,dmlc/mxnet,reminisce/mxnet,yajiedesign/mxnet,tlby/mxnet,ForkedReposBak/mxnet,zhreshold/mxnet,reminisce/mxnet,larroy/mxnet,tlby/mxnet,zhreshold/mxnet,sxjscience/mxnet,eric-haibin-lin/mxnet,yajiedesign/mxnet,eric-haibin-lin/mxnet,eric-haibin-lin/mxnet,reminisce/mxnet,leezu/mxnet,sxjscience/mxnet,larroy/mxnet,yajiedesign/mxnet,szha/mxnet,DickJC123/mxnet,yajiedesign/mxnet,eric-haibin-lin/mxnet,ForkedReposBak/mxnet,sxjscience/mxnet,tlby/mxnet,apache/incubator-mxnet,leezu/mxnet,sxjscience/mxnet,DickJC123/mxnet,reminisce/mxnet,leezu/mxnet,szha/mxnet,zhreshold/mxnet,larroy/mxnet,eric-haibin-lin/mxnet,ForkedReposBak/mxnet,dmlc/mxnet,eric-haibin-lin/mxnet,sxjscience/mxnet,yajiedesign/mxnet,reminisce/mxnet,zhreshold/mxnet,larroy/mxnet,zhreshold/mxnet,tlby/mxnet,tlby/mxnet,leezu/mxnet,szha/mxnet,leezu/mxnet,dmlc/mxnet,eric-haibin-lin/mxnet,larroy/mxnet,szha/mxnet,yajiedesign/mxnet,ForkedReposBak/mxnet,zhreshold/mxnet,tlby/mxnet,sxjscience/mxnet,eric-haibin-lin/mxnet,reminisce/mxnet,reminisce/mxnet,larroy/mxnet,eric-haibin-lin/mxnet,ForkedReposBak/mxnet,szha/mxnet,szha/mxnet,dmlc/mxnet