fix(lint): remove unused BottleImages imports from two test files

pyright strict reportUnusedImport flagged BottleImages in
test_docker_launch_committed_image.py and test_macos_container_launch.py;
neither file references the type by name (they only use the returned
value's attributes).

tests/unit/test_macos_container_launch.py

@@ -11,7 +11,7 @@ from typing import cast
 from unittest.mock import patch
 
 from bot_bottle.agent_provider import AgentProvisionPlan
-from bot_bottle.backend import BottleImages, BottleSpec
+from bot_bottle.backend import BottleSpec
 from bot_bottle.backend.macos_container import launch
 from bot_bottle.backend.macos_container.bottle_plan import MacosContainerBottlePlan
 from bot_bottle.egress import EgressPlan