Keep labels in Field api #2607

comic_feature_view = FeatureView(
    name="comic_featureV1",
    entities=["item_id"],
    ttl=Duration(seconds=86400 * 1),
    features=[
        Feature(name="channel_id", dtype=ValueType.INT32, labels={"default": "14", "desc":"channel"}),
        Feature(name="keyword_weight", dtype=ValueType.FLOAT, labels={"default": "0.0", "desc":"keyword's weight"}),
        Feature(name="comic_vectorv1", dtype=ValueType.FLOAT, labels={"default": ";".join(["0.0" for i in range(32)]), "desc":"deepwalk vector","faiss_index":"/data/faiss_index/comic_featureV1__comic_vectorv1.index"}),
        Feature(name="comic_vectorv2", dtype=ValueType.FLOAT, labels={"default": ";".join(["0.0" for i in range(32)]), "desc":"word2vec vector","faiss_index":"/data/faiss_index/comic_featureV1__comic_vectorv2.index"}),
        Feature(name="gender", dtype=ValueType.INT32, labels={"default": "0", "desc":" 0-femal 1-male"}),
        Feature(name="pub_time", dtype=ValueType.STRING, labels={"default": "1970-01-01 00:00:00", "desc":"comic's publish time"}),
        Feature(name="update_time", dtype=ValueType.STRING, labels={"default": "1970-01-01 00:00:00", "desc":"comic's update time"}),
        Feature(name="view_cnt", dtype=ValueType.INT64, labels={"default": "0", "desc":"comic's hot score"}),
        Feature(name="collect_cnt", dtype=ValueType.INT64, labels={"default": "0", "desc":"collect count"}),
        Feature(name="source_id", dtype=ValueType.INT32, labels={"default": "0", "desc":"comic is from(0-unknown，1-japen，2-usa，3- other)"}),