Keep galaxy.webapps imports local in operations.py

CI on PR galaxyproject#22625 caught this -- packages/test.sh installs galaxy-app on
its own and runs pytest with --doctest-modules, which imports every
source file at collection time. The earlier "Hoist agent-operations
local imports to module level" commit moved
InvocationIndexPayload/WorkflowIndexPayload up alongside the rest, but
galaxy.webapps lives in galaxy-webapps and isn't a galaxy-app
dependency, so those two imports blow up collection with
ModuleNotFoundError.

Restoring just those two as method-local imports (with a comment so we
don't try to hoist them again) gets the package test back to green
without dragging the rest of the cleanup back down.

Author: dannon

lib/galaxy/agents/operations.py

@@ -34,8 +34,10 @@
 from galaxy.schema.workflows import InvokeWorkflowPayload
 from galaxy.structured_app import MinimalManagerApp
 from galaxy.tool_util_models.dynamic_tool_models import DynamicUnprivilegedToolCreatePayload
-from galaxy.webapps.galaxy.services.invocations import InvocationIndexPayload
-from galaxy.webapps.galaxy.services.workflows import WorkflowIndexPayload
+
+# galaxy.webapps lives in a separate package (galaxy-webapps) and is not a
+# dependency of galaxy-app, so these imports must stay local to keep the
+# package-level test suite happy.
 
 log = logging.getLogger(__name__)
 
@@ -443,6 +445,8 @@ def list_workflows(
         show_shared: bool = True,
         search: str | None = None,
     ) -> dict[str, Any]:
+        from galaxy.webapps.galaxy.services.workflows import WorkflowIndexPayload
+
         payload = WorkflowIndexPayload(
             limit=limit,
             offset=offset,
@@ -528,6 +532,8 @@ def get_invocations(
         if history_id:
             decoded_history_id = self.trans.security.decode_id(history_id)
 
+        from galaxy.webapps.galaxy.services.invocations import InvocationIndexPayload
+
         payload = InvocationIndexPayload(
             workflow_id=decoded_workflow_id,
             history_id=decoded_history_id,