remove redundant type conversion (#8692)
remove redundant type conversion (#8692)

Signed-off-by: Christina Jing (荆丽娜) <cd5a64f9f63396f93e08bcf224db563a11d330b4@inspur.com>
GoogleCloudPlatform/prometheus,keegancsmith/prometheus,prometheus/prometheus,GoogleCloudPlatform/prometheus,GoogleCloudPlatform/prometheus,alileza/prometheus,prometheus/prometheus,GoogleCloudPlatform/prometheus,keegancsmith/prometheus,prometheus/prometheus,prometheus/prometheus,keegancsmith/prometheus,prometheus/prometheus,alileza/prometheus,GoogleCloudPlatform/prometheus,keegancsmith/prometheus,alileza/prometheus,alileza/prometheus,keegancsmith/prometheus,alileza/prometheus