ci: Fix workflow failures by updating paths for relocated adk_team samples

The samples in `contributing/samples/adk_documentation` and other `adk_..._agent` directories were moved to `contributing/samples/adk_team/`. This caused workflows to fail with `ModuleNotFoundError` because `PYTHONPATH` was pointing to the old location.
Updated `PYTHONPATH` and module names in 7 workflow files to resolve correctly.

Change-Id: I5495a086b2ddc8f7bbd8c70b529271e06baced91