fix missing db.Close() in web_test.go in order to avoid goroutine leak (#10035)
fix missing db.Close() in web_test.go in order to avoid goroutine leak (#10035)

Signed-off-by: Shihao Xia <a45f275d95accab80f91e3bb04b2ef4f1b3f39ef@hotmail.com>
keegancsmith/prometheus,prometheus/prometheus,prometheus/prometheus,keegancsmith/prometheus,keegancsmith/prometheus,prometheus/prometheus,keegancsmith/prometheus,prometheus/prometheus,prometheus/prometheus,keegancsmith/prometheus