[FIX] hr_leave: validate leave in multi-company environment

Validating an employee's leave with multiple companies selected doesn't
work when the employee isn't part of one of the selected companies

Steps to reproduce:
1. Install Time Off
2. Go to General Settings > Companies and create another company
3. Connect as Marc Demo, open Time Off and create a new time off request
4. Connect as Mitchell Admin and go to Time Off > Managers > Time Off
5. Approve and validate the time off request of Marc Demo
6. An access error is raised: `Access to unauthorized or invalid
   companies.`

Solution:
Clear `allowed_company_ids` from the context when we create the
`calendar.event` to avoid raising the error

Problem:
The creation of the `calendar.event` didn't use the correct user's
`allowed_company_ids` in the context

opw-3052973

closes odoo/odoo#107374

X-original-commit: df01e563
Signed-off-by: Kevin Baptiste <kba@odoo.com>
Signed-off-by: Guillaume Merlin (megu) <megu@odoo.com>

addons/hr_holidays/models/hr_leave.py

@@ -957,6 +957,7 @@ class HolidaysRequest(models.Model):
             Meeting = self.env['calendar.event']
             for user_id, meeting_values in meeting_values_for_user_id.items():
                 meetings += Meeting.with_user(user_id or self.env.uid).with_context(
+                                allowed_company_ids=[],
                                 no_mail_to_attendees=True,
                                 calendar_no_videocall=True,
                                 active_model=self._name