[FIX] web: custom filter on date[time] with changing the operator

On a list view, Add a custom filter on a date
Change the operator to "in between"
Change it back to "equal"
Apply the search

Before this commit, the label of the filter still was in between
Whereas it should have been "equal to ..."

After this commit, the label of the filter is correct

OPW 2085951

closes odoo/odoo#38705

closes odoo/odoo#38869

closes odoo/odoo#38898

Signed-off-by: Lucas Perais (lpe) <lpe@odoo.com>
Signed-off-by: Lucas Perais (lpe) <lpe@odoo.com>
Signed-off-by: Lucas Perais (lpe) <lpe@odoo.com>

addons/web/static/src/js/views/control_panel/search/search_filters.js

@@ -237,7 +237,8 @@ var DateTime = Field.extend({
     },
     toString: function () {
         var str = field_utils.format[this.attributes.type](this.get_value(), {type: this.attributes.type});
-        var date_1_value = this.datewidget_1 && this.get_value(1);
+        // the second datewidget might have been hidden because the operator has changed
+        var date_1_value = this.datewidget_1 && !this.datewidget_1.$el.hasClass('o_hidden') && this.get_value(1);
         if (date_1_value) {
             str += _lt(" and ") + field_utils.format[this.attributes.type](date_1_value, {type: this.attributes.type});
         }