refine: remove data_file_content in FileScanTask (#1485)

## Which issue does this PR close?


I think we don't need data_file_content in FileScanTask seems it's
always be `Data` and the delete file will be stored in `deletes`.

## What changes are included in this PR?



## Are these changes tested?


Co-authored-by: ZENOTME <st810918843@gmail.com>

Author: ZENOTME

crates/iceberg/src/arrow/delete_filter.rs

@@ -334,7 +334,6 @@ pub(crate) mod tests {
                 length: 0,
                 record_count: None,
                 data_file_path: format!("{}/1.parquet", table_location.to_str().unwrap()),
-                data_file_content: DataContentType::Data,
                 data_file_format: DataFileFormat::Parquet,
                 schema: data_file_schema.clone(),
                 project_field_ids: vec![],
@@ -346,7 +345,6 @@ pub(crate) mod tests {
                 length: 0,
                 record_count: None,
                 data_file_path: format!("{}/2.parquet", table_location.to_str().unwrap()),
-                data_file_content: DataContentType::Data,
                 data_file_format: DataFileFormat::Parquet,
                 schema: data_file_schema.clone(),
                 project_field_ids: vec![],

crates/iceberg/src/arrow/reader.rs

@@ -1451,9 +1451,7 @@ mod tests {
     use crate::expr::{Bind, Predicate, Reference};
     use crate::io::FileIO;
     use crate::scan::{FileScanTask, FileScanTaskStream};
-    use crate::spec::{
-        DataContentType, DataFileFormat, Datum, NestedField, PrimitiveType, Schema, SchemaRef, Type,
-    };
+    use crate::spec::{DataFileFormat, Datum, NestedField, PrimitiveType, Schema, SchemaRef, Type};
 
     fn table_schema_simple() -> SchemaRef {
         Arc::new(
@@ -1742,7 +1740,6 @@ message schema {
                 length: 0,
                 record_count: None,
                 data_file_path: format!("{}/1.parquet", table_location),
-                data_file_content: DataContentType::Data,
                 data_file_format: DataFileFormat::Parquet,
                 schema: schema.clone(),
                 project_field_ids: vec![1],

crates/iceberg/src/scan/context.rs

@@ -119,7 +119,6 @@ impl ManifestEntryContext {
             record_count: Some(self.manifest_entry.record_count()),
 
             data_file_path: self.manifest_entry.file_path().to_string(),
-            data_file_content: self.manifest_entry.content_type(),
             data_file_format: self.manifest_entry.file_format(),
 
             schema: self.snapshot_schema,

crates/iceberg/src/scan/mod.rs

@@ -1777,7 +1777,6 @@ pub mod tests {
         );
         let task = FileScanTask {
             data_file_path: "data_file_path".to_string(),
-            data_file_content: DataContentType::Data,
             start: 0,
             length: 100,
             project_field_ids: vec![1, 2, 3],
@@ -1792,7 +1791,6 @@ pub mod tests {
         // with predicate
         let task = FileScanTask {
             data_file_path: "data_file_path".to_string(),
-            data_file_content: DataContentType::Data,
             start: 0,
             length: 100,
             project_field_ids: vec![1, 2, 3],

crates/iceberg/src/scan/task.rs

@@ -41,9 +41,6 @@ pub struct FileScanTask {
     /// The data file path corresponding to the task.
     pub data_file_path: String,
 
-    /// The content type of the file to scan.
-    pub data_file_content: DataContentType,
-
     /// The format of the file to scan.
     pub data_file_format: DataFileFormat,