[FIX] hr: fix the on/off boarding warning in employee

Steps to reproduce:
 - Install Employees App Configuration
 - Got to the Employees > Configuration > Activity Planning > Set the  On/Offboarding Plans
 - Create Test Employee With No Catch
 - Click on Launch Plan action
 - Check the Warning in Launch Plan Wizard

When employee's coach or manager empty then warning is appeared coach's/manager's
user is not set.In this commit we have shown in the warning that the coach/manager
is not set.

task-3193218

closes odoo/odoo#115889

X-original-commit: 421c238129676a83df63f00abadd539e82ced2eb
Signed-off-by: Kevin Baptiste <kba@odoo.com>

addons/hr/i18n/hr.pot

@@ -2546,7 +2546,7 @@ msgstr ""
 #. odoo-python
 #: code:addons/hr/models/hr_plan_activity_type.py:0
 #, python-format
-msgid "User of coach of employee %s is not set."
+msgid "The user of %s's coach is not set."
 msgstr ""
 
 #. module: hr

addons/hr/models/hr_plan_activity_type.py

@@ -44,13 +44,13 @@ class HrPlanActivityType(models.Model):
             if not employee.coach_id:
                 warning = _('Coach of employee %s is not set.', employee.name)
             responsible = employee.coach_id.user_id
-            if not responsible:
-                warning = _('User of coach of employee %s is not set.', employee.name)
+            if employee.coach_id and not responsible:
+                warning = _("The user of %s's coach is not set.", employee.name)
         elif self.responsible == 'manager':
             if not employee.parent_id:
                 warning = _('Manager of employee %s is not set.', employee.name)
             responsible = employee.parent_id.user_id
-            if not responsible:
+            if employee.parent_id and not responsible:
                 warning = _("The manager of %s should be linked to a user.", employee.name)
         elif self.responsible == 'employee':
             responsible = employee.user_id