fix: Fix typo in several files

Merge https://github.com/google/adk-python/pull/3365

**Please ensure you have read the [contribution guide](https://github.com/google/adk-python/blob/main/CONTRIBUTING.md) before creating a pull request.**

fix typo for several files.

### Checklist

- [x] I have read the [CONTRIBUTING.md](https://github.com/google/adk-python/blob/main/CONTRIBUTING.md) document.
- [x] I have performed a self-review of my own code.
- [ ] I have commented my code, particularly in hard-to-understand areas.
- [ ] I have added tests that prove my fix is effective or that my feature works.
- [x] New and existing unit tests pass locally with my changes.
- [x] I have manually tested my changes end-to-end.
- [x] Any dependent changes have been merged and published in downstream modules.

### Additional context

_Add any other context or screenshots about the feature request here._

Co-authored-by: Liang Wu <wuliang@google.com>
COPYBARA_INTEGRATE_REVIEW=https://github.com/google/adk-python/pull/3365 from UlookEE:fix_typo 1469de4ea354d1c205268b999183ee86c9d6a1d5
PiperOrigin-RevId: 827724001

tests/unittests/runners/test_pause_invocation.py

@@ -469,7 +469,7 @@ class TestPauseInvocationWithLlmAgentTree(BasePauseInvocationTest):
 
 
 class TestPauseInvocationWithWithTransferLoop(BasePauseInvocationTest):
-  """Tests the pausing the invocation when the agent transfer forms a loop."""
+  """Tests pausing the invocation when the agent transfer forms a loop."""
 
   @pytest.fixture
   def agent(self) -> LlmAgent: