The cri image service init has a bug where, after getting FSPath for snapshotter_i, it stores it under defaultSnapshotter instead of snapshotter_i. Also make a few other refactor: 1. Dedup the snapshotRoot loading for defaultSnapshotter 2. Remove some unnecessary logic in RuntimePlatforms for-loop Signed-off-by: Jin Dong <djdongjin95@gmail.com>