Fix relative indentation when pasting content copied from outside Zed (#25300)

Closes https://github.com/zed-industries/zed/issues/24914

Release Notes:

- Fixed incorrect indentation when pasting multi-line content that was
copied from another app.

crates/assistant_context_editor/src/patch.rs

@@ -140,7 +140,7 @@ impl ResolvedPatch {
             buffer.edit(
                 edits,
                 Some(AutoindentMode::Block {
-                    original_indent_columns: Vec::new(),
+                    original_start_columns: Vec::new(),
                 }),
                 cx,
             );