fix: remove deprecated squid filebeat module tutorial from integrations (#191115)

## Summary

This PR removes the deprecated `squid` integration based on the Filebeat
module (deprecation issue
[here](https://github.com/elastic/beats/issues/37746)). Instead, as of
now, a user that wants to use the `squad` integration needs to tick the
`Display beta integrations` and install the "new" squid integration


### Risk Matrix

N/A


### For maintainers

- [ ] This was checked for breaking API changes and was [labeled
appropriately](https://www.elastic.co/guide/en/kibana/master/contributing.html#kibana-release-notes-process)

test/api_integration/apis/custom_integration/integrations.ts

@@ -40,7 +40,7 @@ export default function ({ getService }: FtrProviderContext) {
 
         expect(resp.body).to.be.an('array');
 
-        expect(resp.body.length).to.be(109); // the beats
+        expect(resp.body.length).to.be(108); // the beats
       });
     });
   });