Update broken redis tests (#12371)

Update broken redis tests -- tiny PR :) 
- **Description:** Fixes Redis tests on master (look like it was broken
by https://github.com/langchain-ai/langchain/pull/11257)
  - **Issue:** None,
  - **Dependencies:** No
  - **Tag maintainer:** @baskaryan @Spartee 
  - **Twitter handle:** N/A

Co-authored-by: Sam Partee <sam.partee@redis.com>

libs/langchain/tests/integration_tests/vectorstores/test_redis.py

@@ -141,7 +141,8 @@ def test_custom_keys(texts: List[str]) -> None:
     docsearch, keys_out = Redis.from_texts_return_keys(
         texts, FakeEmbeddings(), redis_url=TEST_REDIS_URL, keys=keys_in
     )
-    assert keys_in == keys_out
+    # it will append the index key prefix to all keys
+    assert keys_out == [docsearch.key_prefix + ":" + key for key in keys_in]
     assert drop(docsearch.index_name)
 
 
@@ -154,11 +155,13 @@ def test_custom_keys_from_docs(texts: List[str]) -> None:
     )
     client = docsearch.client
     # test keys are correct
-    assert client.hget("test_key_1", "content")
+    assert client.hget(docsearch.key_prefix + ":" + "test_key_1", "content")
     # test metadata is stored
-    assert client.hget("test_key_1", "a") == bytes("b", "utf-8")
+    assert client.hget(docsearch.key_prefix + ":" + "test_key_1", "a") == bytes(
+        "b", "utf-8"
+    )
     # test all keys are stored
-    assert client.hget("test_key_2", "content")
+    assert client.hget(docsearch.key_prefix + ":" + "test_key_2", "content")
     assert drop(docsearch.index_name)