[FIX] web: wrong day column title in arabic

In arabic, with the version localization of bootstrap we use the week
starts on saturday. But the version of bootstrap-datetimepicker we use
in 10.0 and saas-14 is 3.0.3 which only fully supports week starting
on sunday and monday.

Thus in arabic, the column title in the date picker would be:

  Sunday <- Monday (ﻥ, ﺙ, ﺭ, ﺥ, ﺝ, ﺱ, ﺡ)

Instead of what the numbered days in the calendar are shown as:
  Friday <- Saturday (ﺱ, ﺡ, ﻥ, ﺙ, ﺭ, ﺥ, ﺝ)

This issue doesn't happen in saas-15, 11.0 and over since the library
has been updated with ad6fd5f8 and the as of version 4 supports any
starting day of week, with this change:
 https://github.com/Eonasdan/bootstrap-datetimepicker/commit/557b657

opw-1825640
closes #24200

addons/web/static/lib/bootstrap-datetimepicker/src/js/bootstrap-datetimepicker.js

@@ -391,18 +391,14 @@ THE SOFTWARE.
             if (picker.options.calendarWeeks === true) {
                 html.append('<th class="cw">#</th>');
             }
-            if (moment().localeData()._week.dow === 0) { // starts on Sunday
-                for (i = 0; i < 7; i++) {
-                    html.append('<th class="dow">' + weekdaysMin[i] + '</th>');
-                }
-            } else {
-                for (i = 1; i < 8; i++) {
-                    if (i === 7) {
-                        html.append('<th class="dow">' + weekdaysMin[0] + '</th>');
-                    } else {
-                        html.append('<th class="dow">' + weekdaysMin[i] + '</th>');
-                    }
-                }
+            // ODOO change so week starting not on sunday/monday have correct
+            // day name. This is solved in saas-15 by using new library version
+            var startDay = moment().localeData()._week.dow;
+            if (startDay === undefined) {
+                startDay = 1;
+            }
+            for (i = startDay; i < startDay + 7; i++) {
+                html.append('<th class="dow">' + weekdaysMin[i % 7] + '</th>');
             }
             picker.widget.find('.datepicker-days thead').append(html);
         },