Make code block eval resilient to indentation (#29633)

This reduces spurious failures in the eval.

Release Notes:

- N/A

crates/assistant_tools/src/edit_file_tool.rs

@@ -174,7 +174,6 @@ impl Tool for EditFileTool {
                     "The `old_string` and `new_string` are identical, so no changes would be made."
                 ));
             }
-            let old_string = input.old_string.clone();
 
             let result = cx
                 .background_spawn(async move {
@@ -214,21 +213,6 @@ impl Tool for EditFileTool {
                             input.path.display()
                         )
                     } else {
-                        let old_string_with_buffer = format!(
-                            "old_string:\n\n{}\n\n-------file-------\n\n{}",
-                            &old_string,
-                            buffer.text()
-                        );
-                        let path = {
-                            use std::collections::hash_map::DefaultHasher;
-                            use std::hash::{Hash, Hasher};
-
-                            let mut hasher = DefaultHasher::new();
-                            old_string_with_buffer.hash(&mut hasher);
-
-                            PathBuf::from(format!("failed_tool_{}.txt", hasher.finish()))
-                        };
-                        std::fs::write(path, old_string_with_buffer).unwrap();
                         anyhow!("Failed to match the provided `old_string`")
                     }
                 })?;