chore(generative_ai): remove deprecated samples migrated to genai (#14500)

These samples are no longer in use in devsite. They have been migrated
 to genai with new region tags and updated code.

Author: XrossFox

generative_ai/evaluation/pairwise_summarization_quality.py

@@ -13,14 +13,8 @@
 # limitations under the License.
 
 import get_rouge_score
-import pairwise_summarization_quality
 
 
 def test_create_evaluation_task() -> None:
     response = get_rouge_score.get_rouge_score()
     assert response
-
-
-def test_pairwise_evaluation_summarization_quality() -> None:
-    response = pairwise_summarization_quality.evaluate_output()
-    assert response