fix(llmobs): [MLOB-3857] avoid importing from genai on startup (#14542)

This PR resolves an issue where Google Genai LLM spans were missing from
Pydantic AI traces because we were importing from `google.genai.types`
from within the Google GenAI integration upon startup. This was causing
Google GenAI to not be patched when it was imported from within the
Pydantic AI library.

I have moved the import causing this issue into the method where it is
used to avoid this issue.

| Before | After |
| --- | --- |
| <img width="2746" height="590" alt="image"
src="https://github.com/user-attachments/assets/1ada34f4-7b48-4997-80c0-f63d7067105e"
/> | <img width="2746" height="614" alt="image"
src="https://github.com/user-attachments/assets/a68dc13c-c0fb-4eda-885a-13042910b093"
/> (note it is expected that the execution flow viz is not available
because there are no span links implemented yet for GenAI tool calls) |

## Checklist
- [x] PR author has checked that all the criteria below are met
- The PR description includes an overview of the change
- The PR description articulates the motivation for the change
- The change includes tests OR the PR description describes a testing
strategy
- The PR description notes risks associated with the change, if any
- Newly-added code is easy to change
- The change follows the [library release note
guidelines](https://ddtrace.readthedocs.io/en/stable/releasenotes.html)
- The change includes or references documentation updates if necessary
- Backport labels are set (if
[applicable](https://ddtrace.readthedocs.io/en/latest/contributing.html#backporting))

## Reviewer Checklist
- [x] Reviewer has checked that all the criteria below are met 
- Title is accurate
- All changes are related to the pull request's stated goal
- Avoids breaking
[API](https://ddtrace.readthedocs.io/en/stable/versioning.html#interfaces)
changes
- Testing strategy adequately addresses listed risks
- Newly-added code is easy to change
- Release note makes sense to a user of the library
- If necessary, author has acknowledged and discussed the performance
implications of this PR as reported in the benchmarks PR comment
- Backport labels are set in a manner that is consistent with the
[release branch maintenance
policy](https://ddtrace.readthedocs.io/en/latest/contributing.html#backporting)

Author: ncybul

ddtrace/llmobs/_integrations/google_genai.py

@@ -3,12 +3,6 @@
 from typing import List
 from typing import Optional
 
-
-try:
-    from google.genai.types import FunctionDeclaration
-except ImportError:
-    FunctionDeclaration = None
-
 from ddtrace._trace.span import Span
 from ddtrace.llmobs._constants import INPUT_DOCUMENTS
 from ddtrace.llmobs._constants import INPUT_MESSAGES
@@ -187,6 +181,10 @@ def _function_declaration_to_tool_definition(self, function_declaration) -> Tool
         )
 
     def _extract_tools(self, config) -> List[ToolDefinition]:
+        try:
+            from google.genai.types import FunctionDeclaration
+        except ImportError:
+            FunctionDeclaration = None
         tool_definitions = []
         tools = _get_attr(config, "tools", []) or []
         for tool in tools:

releasenotes/notes/fix-genai-import-issue-8b90aeaea96f4a58.yaml

@@ -0,0 +1,4 @@
+fixes:
+  - |
+    LLM Observability: Fixes an issue where certain Google GenAI LLM requests were not being traced due to importing from
+    google.genai.types on startup.