Fix remaining issues after gopls modernize formatting (#34771)

Followup https://github.com/go-gitea/gitea/pull/34751, fix all remaining
marked issues.

---------

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

routers/install/install.go

@@ -99,11 +99,7 @@ func Install(ctx *context.Context) {
 	form.SSLMode = setting.Database.SSLMode
 
 	curDBType := setting.Database.Type.String()
-	var isCurDBTypeSupported bool
-	if slices.Contains(setting.SupportedDatabaseTypes, curDBType) {
-		isCurDBTypeSupported = true
-	}
-	if !isCurDBTypeSupported {
+	if !slices.Contains(setting.SupportedDatabaseTypes, curDBType) {
 		curDBType = "mysql"
 	}
 	ctx.Data["CurDbType"] = curDBType