[FIX] partner_autocomplete: update log when sending partner to sync fails

In the start_sync method, the logger is updated to use the 'warning' level
instead of the 'error' level. This change reflects a less severe logging level
for cases where sending a partner to sync fails.

The changes have been made to reduce the noise level in the sentry.

sentry-3955309841

closes odoo/odoo#126111

X-original-commit: c1b608c2d28962ed0ccbf15e9eeb2ecf5281b758
Signed-off-by: Louis Baudoux (lba) <lba@odoo.com>

addons/partner_autocomplete/models/res_partner_autocomplete_sync.py

@@ -27,7 +27,7 @@ class ResPartnerAutocompleteSync(models.Model):
                 params['vat'] = partner.vat
                 _, error = self.env['iap.autocomplete.api']._request_partner_autocomplete('update', params)
                 if error:
-                    _logger.error('Send Partner to sync failed: %s' % str(error))
+                    _logger.warning('Send Partner to sync failed: %s', str(error))
 
             to_sync_item.write({'synched': True})