[FIX] google_gmail: do not copy the authorization code

Bug
===
When we copy a GMail outgoing / incoming mail server, an error
occurs because we try to refetch the access token, based on the same
authorization code (which can be used only once).

To fix this issue, we do not copy the authorization code (and other
related fields).

Task-2751996

X-original-commit: 2879976
Part-of: #87294

addons/google_gmail/models/google_gmail_mixin.py

@@ -17,10 +17,10 @@ class GoogleGmailMixin(models.AbstractModel):
     _SERVICE_SCOPE = 'https://mail.google.com/'
 
     use_google_gmail_service = fields.Boolean('Gmail Authentication')
-    google_gmail_authorization_code = fields.Char(string='Authorization Code', groups='base.group_system')
-    google_gmail_refresh_token = fields.Char(string='Refresh Token', groups='base.group_system')
-    google_gmail_access_token = fields.Char(string='Access Token', groups='base.group_system')
-    google_gmail_access_token_expiration = fields.Integer(string='Access Token Expiration Timestamp', groups='base.group_system')
+    google_gmail_authorization_code = fields.Char(string='Authorization Code', groups='base.group_system', copy=False)
+    google_gmail_refresh_token = fields.Char(string='Refresh Token', groups='base.group_system', copy=False)
+    google_gmail_access_token = fields.Char(string='Access Token', groups='base.group_system', copy=False)
+    google_gmail_access_token_expiration = fields.Integer(string='Access Token Expiration Timestamp', groups='base.group_system', copy=False)
     google_gmail_uri = fields.Char(compute='_compute_gmail_uri', string='URI', help='The URL to generate the authorization code from Google', groups='base.group_system')
 
     @api.depends('google_gmail_authorization_code')