[FIX] crm: remove no longer used code.

The code removed by this revision was initally introduced in
odoo/odoo@126ba0a9a8

The `_get_view` override introduced relied
on the context key `opportunity_id`,
which was set in the crm.phonecall form view with
```xml
<field name="opportunity_id" on_change="on_change_opportunity(opportunity_id)" context="{'opportunity_id': opportunity_id}"/>
```
as you can see in the above mentioned revision.

This above node was removed 7 years ago in revision
https://github.com/odoo/odoo/commit/ff2b14d4c3c5aaa62418b527585d0a19e98a23de#diff-892062d6151c1e1c1cb5f6c09035df1d5ae6d5a71f7558aacfdc8cf62627bf5fL138
Therefore making pointless the code about it in the `_get_view`
override.

In addition to this clue to make sure the override is pointless,
checking the code, we can see it relies on `get_formview_action`
to set a different view according to the result of `get_formview_action`.

Since revision
https://github.com/odoo/odoo/commit/e28d3aa4d3851d72deba08c236072d002f83216a#diff-595d3dbbabdc4f766a380a320c1c1a43b143385bc7487c7275e80f76a9fbabc2L1224
the override of `get_formview_id` is removed,
therefore making `get_formview_action` of `crm.lead` completely default
(as there is no override of `get_formview_action` either in crm.lead,
nor any dependent method)

We can therefore assume this code was useless,
at least in standard odoo,
and can therefore be removed.

X-original-commit: 82c2f4b13034c16ca5546afd777150ecb4d8ad9b
Part-of: odoo/odoo#103438

addons/crm/models/crm_lead.py

@@ -903,11 +903,6 @@ class Lead(models.Model):
 
     @api.model
     def _get_view(self, view_id=None, view_type='form', **options):
-        if self._context.get('opportunity_id'):
-            opportunity = self.browse(self._context['opportunity_id'])
-            action = opportunity.get_formview_action()
-            if action.get('views') and any(view_id for view_id in action['views'] if view_id[1] == view_type):
-                view_id = next(view_id[0] for view_id in action['views'] if view_id[1] == view_type)
         arch, view = super()._get_view(view_id, view_type, **options)
         if view_type == 'form':
             arch = self._view_get_address(arch)