[BugFix] Fix some bug of light schema change (StarRocks#30485)

This pr fixes some bugs:

This pr([Feature] Support light schema change of adding and dropping columns StarRocks#26246) supports light schema change and we add tablet schema in rowset meta. But in the course of multiple conflict resolution, the associated logic is lost. In addition, this pr change the location num of tablet_schema in RowsetMetaPB for better compatibility.
When we create a column iterator in segment, if we provide tablet schema in read options, we should use the given tablet schema in create column iterator.

Signed-off-by: zhangqiang <qiangzh95@gmail.com>

be/src/storage/rowset/rowset_writer.cpp

@@ -210,6 +210,11 @@ StatusOr<RowsetSharedPtr> RowsetWriter::build() {
     } else {
         _rowset_meta_pb->set_rowset_state(VISIBLE);
     }
+    // we don't support light schema change for primary key table so far, skip it
+    if (_context.tablet_schema->keys_type() != KeysType::PRIMARY_KEYS) {
+        _context.tablet_schema->to_schema_pb(_rowset_meta_pb->mutable_tablet_schema());
+    }
+
     auto rowset_meta = std::make_shared<RowsetMeta>(_rowset_meta_pb);
     RowsetSharedPtr rowset;
     RETURN_IF_ERROR(

be/src/storage/rowset/segment.cpp

@@ -236,7 +236,6 @@ StatusOr<ChunkIteratorPtr> Segment::_new_iterator(const Schema& schema, const Se
         }
         if (!_column_readers.at(column_unique_id)->segment_zone_map_filter(pair.second)) {
             // skip segment zonemap filter when this segment has column files link to it.
-            const TabletColumn& tablet_column = _tablet_schema->column(column_id);
             if (tablet_column.is_key() || _use_segment_zone_map_filter(read_options)) {
                 read_options.stats->segment_stats_filtered += _column_readers.at(column_unique_id)->num_rows();
                 return Status::EndOfFile(strings::Substitute("End of file $0, empty iterator", _fname));

gensrc/proto/olap_file.proto

@@ -144,8 +144,6 @@ message RowsetMetaPB {
     optional int64 num_segments = 22;
     // rowset id definition, it will replace required rowset id
     optional string rowset_id = 23;
-    // tablet meta pb, for compaction
-    optional TabletSchemaPB tablet_schema = 24;
     // to indicate whether the data between the segments overlap
     optional SegmentsOverlapPB segments_overlap_pb = 51 [default = OVERLAP_UNKNOWN];
     // every segment in a rowset has an unique uint32 id
@@ -168,6 +166,8 @@ message RowsetMetaPB {
     optional int64 total_update_row_size = 58;
     // true if it is generated by partial_schema_change
     optional bool partial_schema_change = 59;
+    // tablet meta pb, for compaction
+    optional TabletSchemaPB tablet_schema = 60;
 }
 
 enum DataFileType {