Consecutive Event field widget reloads the whole form on ajax

Problem/Motivation

Editing event dates with "Consecutive Event" recurring type selected reloads the whole form via ajax, although it seems not necessary.

In our case, we're using multiple tabs provided by Field Group module. "Date" fields are located in one of the tabs, so once we change something in "Consecutive Event", the form is reloaded and active tab is refreshed as well.

Steps to reproduce

1) Install Field Group;
2) In the "Manage form display" add Tabs component and add "Recur Type" and "Consecutive Event" to the 2nd tab;
3) Go to new event page, go to the tab with date fields and trigger ajax reload;
4) You should see the form reload and lose the active tab;

Proposed resolution

I don't get why the ajax reload is necessary, but if it's required, let's refresh only the widget form components.

Remaining tasks

Review and manual testing.