refact(data-viz): remove X/Y/Color input auto-update

Finally I don't think it brings a lot to update automatically
the selected variables, also it was
not correctly implemented.

src/fun/func_data-viz.R

@@ -58,15 +58,12 @@ data_viz_server <- function(id, plot_data) {
       var_list <- c(none_value, var_list)
       updateSelectInput(session, "x_var",
         choices = var_list,
-        selected = ifelse(!is_null_var(input$x_var) && input$x_var %in% var_list, input$x_var, var_list[2])
       )
       updateSelectInput(session, "y_var",
         choices = var_list,
-        selected = ifelse(!is_null_var(input$x_var) && input$y_var %in% var_list, input$y_var, var_list[1])
       )
       updateSelectInput(session, "col_var",
         choices = var_list,
-        selected = ifelse(!is_null_var(input$x_var) && input$col_var %in% var_list, input$col_var, var_list[1])
       )
     })