fix(LiteLlm): recognize assistant- prefix as valid OpenAI file ID

Merge #5758

Original PR by @nileshpatil6 (Nilesh Patil <128893479+nileshpatil6@users.noreply.github.com>)

Azure OpenAI files receive IDs with an `assistant-` prefix (e.g. `assistant-abc123`) or `file-` prefix. When `_looks_like_openai_file_id` recognizes an `assistant-` prefixed ID (e.g., `assistant-abc123`) or `file-` prefixed ID, `_redact_file_uri_for_log` defaulted to logging both as `file - <redacted>`.

Fix: refactor `_redact_file_uri_for_log` to dynamically extract file ID prefixes (`file-`, `assistant-`). This ensures compatibility with both current prefixes and future OpenAI/Azure file ID types.

Fixes #5664

Co-authored-by: Yi Liu <yiliuly@google.com>
PiperOrigin-RevId: 933931477

Author: 2 people

src/google/adk/models/lite_llm.py

@@ -398,7 +398,8 @@ def _redact_file_uri_for_log(
   if file_uri.startswith("assistant-"):
     return "assistant-<redacted>"
   if _looks_like_openai_file_id(file_uri):
-    return "file-<redacted>"
+    prefix = file_uri.split("-", 1)[0]
+    return f"{prefix}-<redacted>"
   try:
     parsed = urlparse(file_uri)
   except ValueError: