chore: update to bytes for better compactibility

Author: shuiyisong

c++/greptime/v1/common.pb.cc

@@ -58,12 +58,10 @@ message Token { string token = 1; }
 
 message AffectedRows { uint32 value = 1; }
 
-message Metrics {
-  string metrics = 1;
-}
+message Metrics { bytes metrics = 1; }
 
-message FlightMetadata { 
-  AffectedRows affected_rows = 1; 
+message FlightMetadata {
+  AffectedRows affected_rows = 1;
   Metrics metrics = 2;
 }
 
@@ -121,9 +119,7 @@ message Decimal128 {
 
 // Type extension for some complex types
 message ColumnDataTypeExtension {
-  oneof type_ext {
-    DecimalTypeExtension decimal_type = 1;
-  }
+  oneof type_ext { DecimalTypeExtension decimal_type = 1; }
 }
 
 message DecimalTypeExtension {