Do not create empty ".ssh" directory when loading config (#20289)

Creating the directory automatically is not correct.
In other places for ssh key writing (RewriteAllPrincipalKeys / appendAuthorizedKeysToFile, etc), the directory will still be created when updating the keys.
This PR will resolve the confusing and annoying problem: the dummy and empty ".ssh" directory in new git home.

modules/setting/setting.go

@@ -859,9 +859,7 @@ func loadFromConf(allowEmpty bool, extraConfig string) {
 	SSH.AuthorizedPrincipalsAllow, SSH.AuthorizedPrincipalsEnabled = parseAuthorizedPrincipalsAllow(sec.Key("SSH_AUTHORIZED_PRINCIPALS_ALLOW").Strings(","))
 
 	if !SSH.Disabled && !SSH.StartBuiltinServer {
-		if err := os.MkdirAll(SSH.RootPath, 0o700); err != nil {
-			log.Fatal("Failed to create '%s': %v", SSH.RootPath, err)
-		} else if err = os.MkdirAll(SSH.KeyTestPath, 0o644); err != nil {
+		if err = os.MkdirAll(SSH.KeyTestPath, 0o644); err != nil {
 			log.Fatal("Failed to create '%s': %v", SSH.KeyTestPath, err)
 		}