agent: Don't stop following after edits (#32606)

This is reverting a change from #32071 which caused agent following to
stop after the file was edited.

This will reintroduce the behavior that the keyboard shortcuts don't
work until the model is done generating, but we will revisit that
afterwards.

Co-authored-by: Bennet Bo Fenner <bennetbo@gmx.de>

Release Notes:

- agent: Fix a regression in agent following behavior after file edits

Co-authored-by: Bennet Bo Fenner <bennetbo@gmx.de>

crates/agent/src/agent_diff.rs

@@ -1513,7 +1513,7 @@ impl AgentDiff {
                     multibuffer.add_diff(diff_handle.clone(), cx);
                 });
 
-                let new_state = if thread.read(cx).has_pending_edit_tool_uses() {
+                let new_state = if thread.read(cx).is_generating() {
                     EditorState::Generating
                 } else {
                     EditorState::Reviewing