fix: [2.5] Ref collection meta when load l0 segment meta only (milvus…

…-io#37181)

Cherry-pick from master
pr: milvus-io#37178
Related to milvus-io#37177

Previous PR milvus-io#37160

Collection meta is not ref-ed when loading l0 segment in `RemoteLoad`
policy, which cause collection meta release when lots of l0 segment
released.

Signed-off-by: Congqi Xia <congqi.xia@zilliz.com>