enhance: Add L2 segment level (milvus-io#29595)

milvus-io#28410

Signed-off-by: wayblink <[email protected]>

internal/proto/data_coord.proto

@@ -25,6 +25,7 @@ enum SegmentLevel {
   Legacy = 0; // zero value for legacy logic
   L0 = 1; // L0 segment, contains delta data for current channel
   L1 = 2; // L1 segment, normal segment, with no extra compaction attribute
+  L2 = 3; // L2 segemnt, segment with extra data distribution info
 }
 
 service DataCoord {
@@ -317,7 +318,7 @@ message SegmentInfo {
   bool compacted = 19;
 
   // Segment level, indicating compaction segment level
-  // Available value: Legacy, L0, L1
+  // Available value: Legacy, L0, L1, L2
   // For legacy level, it represent old segment before segment level introduced
   // so segments with Legacy level shall be treated as L1 segment
   SegmentLevel level = 20;