Minor add ticket references to deprecated code (#14174)

Author: alamb

datafusion/proto-common/src/from_proto/mod.rs

@@ -321,6 +321,7 @@ impl TryFrom<&protobuf::Field> for Field {
     fn try_from(field: &protobuf::Field) -> Result<Self, Self::Error> {
         let datatype = field.arrow_type.as_deref().required("arrow_type")?;
         let field = if field.dict_id != 0 {
+            // https://github.com/apache/datafusion/issues/14173
             #[allow(deprecated)]
             Self::new_dict(
                 field.name.as_str(),
@@ -436,6 +437,7 @@ impl TryFrom<&protobuf::ScalarValue> for ScalarValue {
                     let id = dict_batch.id();
 
                     let fields_using_this_dictionary = {
+                        // See https://github.com/apache/datafusion/issues/14173
                         #[allow(deprecated)]
                         schema.fields_with_dict_id(id)
                     };

datafusion/proto-common/src/to_proto/mod.rs

@@ -98,6 +98,7 @@ impl TryFrom<&Field> for protobuf::Field {
             children: Vec::new(),
             metadata: field.metadata().clone(),
             #[allow(deprecated)]
+            // See https://github.com/apache/datafusion/issues/14173 to remove deprecated dict_id
             dict_id: field.dict_id().unwrap_or(0),
             dict_ordered: field.dict_is_ordered().unwrap_or(false),
         })

datafusion/proto/tests/cases/roundtrip_logical_plan.rs

@@ -1815,7 +1815,7 @@ fn round_trip_datatype() {
     }
 }
 
-// TODO file a ticket about handling deprecated dict_id attributes
+// See https://github.com/apache/datafusion/issues/14173 to remove deprecated dict_id
 #[allow(deprecated)]
 #[test]
 fn roundtrip_dict_id() -> Result<()> {