community: callbacks guard_imports (#21173)

Issue: we have several helper functions to import third-party libraries
like import_uptrain in
[community.callbacks](https://api.python.langchain.com/en/latest/callbacks/langchain_community.callbacks.uptrain_callback.import_uptrain.html#langchain_community.callbacks.uptrain_callback.import_uptrain).
And we have core.utils.utils.guard_import that works exactly for this
purpose.
The import_<package> functions work inconsistently and rather be private
functions.
Change: replaced these functions with the guard_import function.

Related to #21133

libs/community/langchain_community/callbacks/infino_callback.py

@@ -5,32 +5,17 @@ from langchain_core.agents import AgentAction, AgentFinish
 from langchain_core.callbacks import BaseCallbackHandler
 from langchain_core.messages import BaseMessage
 from langchain_core.outputs import ChatGeneration, LLMResult
+from langchain_core.utils import guard_import
 
 
 def import_infino() -> Any:
     """Import the infino client."""
-    try:
-        from infinopy import InfinoClient
-    except ImportError:
-        raise ImportError(
-            "To use the Infino callbacks manager you need to have the"
-            " `infinopy` python package installed."
-            "Please install it with `pip install infinopy`"
-        )
-    return InfinoClient()
+    return guard_import("infinopy").InfinoClient()
 
 
 def import_tiktoken() -> Any:
     """Import tiktoken for counting tokens for OpenAI models."""
-    try:
-        import tiktoken
-    except ImportError:
-        raise ImportError(
-            "To use the ChatOpenAI model with Infino callback manager, you need to "
-            "have the `tiktoken` python package installed."
-            "Please install it with `pip install tiktoken`"
-        )
-    return tiktoken
+    return guard_import("tiktoken")
 
 
 def get_num_tokens(string: str, openai_model_name: str) -> int: