Revert unrelated changes for SMTP auth (#21767) (#21768)

Backport #21767

The purpose of #18982 is to improve the SMTP mailer, but there were some
unrelated changes made to the SMTP auth in
https://github.com/go-gitea/gitea/pull/18982/commits/d60c43869420f5fc43ad19b454c9ae50dad65964

This PR reverts these unrelated changes, fix #21744

Co-authored-by: Lunny Xiao <xiaolunwen@gmail.com>

cmd/admin.go

@@ -413,9 +413,9 @@ var (
 			Usage: "SMTP Authentication Type (PLAIN/LOGIN/CRAM-MD5) default PLAIN",
 		},
 		cli.StringFlag{
-			Name:  "addr",
+			Name:  "host",
 			Value: "",
-			Usage: "SMTP Addr",
+			Usage: "SMTP Host",
 		},
 		cli.IntFlag{
 			Name:  "port",
@@ -955,8 +955,8 @@ func parseSMTPConfig(c *cli.Context, conf *smtp.Source) error {
 		}
 		conf.Auth = c.String("auth-type")
 	}
-	if c.IsSet("addr") {
-		conf.Addr = c.String("addr")
+	if c.IsSet("host") {
+		conf.Host = c.String("host")
 	}
 	if c.IsSet("port") {
 		conf.Port = c.Int("port")