Fix convergence issue for lectures in recurring cycles

Lectures convergent in the first cycle do not behave as expected in subsequent cycles. Even though the lectures appear visually as convergent in later cycles, the guest list is not shared between them. This causes inconsistencies, such as:

• In the calendar event popup, both calendars are shown as selected, but the calendar counter incorrectly shows "10 selected" instead of "2".

• Guests are not synced across the convergent lectures of the two courses in subsequent cycles.

Expected Behavior:

• Convergent lectures across all cycles should correctly share guest data.

• The calendar counter in the event popup should reflect the actual number of selected calendars.

• In this way Teacher has to join lecture of both courses because event meet room are differents on cycles differents from 1st one

Steps to Reproduce:

1. Create two courses with convergent lectures in the first cycle.

2. Create subsequent cycles with the same setup.

3. Open the calendar and check the guest list and calendar selection in the event popup for later cycles.

How lecture-event popup appear in 1st cycle for a converged lecture

How lecture-event popup appear in 2nd cycle for a converged lecture