langchain-community[major]: Upgrade community to pydantic 2 (#26011)

This PR upgrades langchain-community to pydantic 2.


* Most of this PR was auto-generated using code mods with gritql
(https://github.com/eyurtsev/migrate-pydantic/tree/main)
* Subsequently, some code was fixed manually due to accommodate
differences between pydantic 1 and 2

Breaking Changes:

- Use TEXTEMBED_API_KEY and TEXTEMBEB_API_URL for env variables for text
embed integrations:
cbea780492

Other changes:

- Added pydantic_settings as a required dependency for community. This
may be removed if we have enough time to convert the dependency into an
optional one.

---------

Co-authored-by: Eugene Yurtsev <eyurtsev@gmail.com>
Co-authored-by: Bagatur <baskaryan@gmail.com>

libs/community/langchain_community/llms/ctranslate2.py

@@ -3,8 +3,8 @@ from typing import Any, Dict, List, Optional, Union
 from langchain_core.callbacks import CallbackManagerForLLMRun
 from langchain_core.language_models.llms import BaseLLM
 from langchain_core.outputs import Generation, LLMResult
-from langchain_core.pydantic_v1 import Field
 from langchain_core.utils import pre_init
+from pydantic import Field
 
 
 class CTranslate2(BaseLLM):