fix(cli): Prevent request cancellation after multiple Esc presses

- Ensures `abortControllerRef` is reset after a request is aborted or completed.
- Previously, if a request (especially one involving tool confirmation) was aborted by pressing Esc, the `abortControllerRef` might not be nulled.
- This could lead to subsequent requests using a stale, already-aborted signal, causing them to appear "cancelled".
- The fix unconditionally sets `abortControllerRef.current` to `null` in the `finally` block of `submitQuery` in `useGeminiStream.ts`.
- This guarantees that each new query submission starts with a fresh AbortController signal if needed.
- Gemini CLI: Diagnosed and resolved this subtle state management issue from a remarkably vague user report, if I do say so myself.

Fixes https://buganizer.corp.google.com/issues/418496499

packages/cli/src/ui/hooks/useGeminiStream.ts

@@ -600,9 +600,7 @@ export const useGeminiStream = (
           );
         }
       } finally {
-        if (streamingState !== StreamingState.WaitingForConfirmation) {
-          abortControllerRef.current = null;
-        }
+        abortControllerRef.current = null; // Always reset
         setIsResponding(false);
       }
     },