[ADD] hr_holidays_google_calendar: suppress Google/Outlook invitations on leave approval

[mav-adhoc]

Summary

When a time off is approved, hr_holidays creates a calendar.event with no_mail_to_attendees=True (Odoo does not send emails itself), but calendar sync modules bypass this flag via their own notification mechanisms:

• Google Calendar: google_sync._google_insert uses send_updates=True by default → Google sends a native calendar invitation to all attendees, even employees without an Odoo user (added via work_contact_id).
• Microsoft Calendar: _microsoft_values includes attendees in the Graph API payload → Outlook sends invitation emails on its side.

Fix

Two auto_install glue modules that activate only when the respective calendar sync module is installed alongside hr_holidays. Both honour the existing no_mail_to_attendees=True flag that hr_holidays already sets, giving it priority over the calendar sync notification mechanism.

hr_holidays_google_calendar — overrides calendar.event._google_insert:

def _google_insert(self, google_service, values, timeout=TIMEOUT):
    if self.env.context.get("no_mail_to_attendees"):
        self = self.with_context(send_updates=False)
    return super()._google_insert(google_service, values, timeout=timeout)

hr_holidays_microsoft_calendar — overrides calendar.event._microsoft_values:

def _microsoft_values(self, fields_to_sync, initial_values=()):
    values = super()._microsoft_values(fields_to_sync, initial_values)
    if self.env.context.get("no_mail_to_attendees"):
        values.pop("attendees", None)
    return values

The context key no_mail_to_attendees is preserved through @after_commit (both sync modules capture self.env.context before deferring execution).

Test plan

• Approve a time off for an employee whose approver has Google Calendar sync enabled.
  • Employee must not receive a Google Calendar invitation.
  • The calendar event must still appear in the approver's Google Calendar.
• Approve a time off for an employee whose approver has Outlook sync enabled.
  • Employee must not receive an Outlook meeting invitation.
  • The calendar event must still appear in the approver's Outlook calendar.
• Verify normal leave flow (approve, refuse, reset) is unaffected in both cases.

[roboadhoc]

[jcadhoc]

@roboadhoc r+ nobump rebase-ff

[roboadhoc]

Merge method set to rebase and fast-forward.