刪除集合
方案一：
def delete_collection():
from pymilvus import utility
utility.drop_collection(settings.MILVUS_CONFIG.collection.name)
方案二：
from core.milvus.models import collection
conn = connections._fetch_handler('default')
if conn.has_collection(settings.MILVUS_CONFIG.collection.name):
logger.debug('集合已存在')
collection.drop()