[Serverless]: Troubleshooting page should also include some Serverless specific troubleshooting tips

### Serverless Docs

Elastic Security Serverless

### Description

https://www.elastic.co/docs/current/serverless/security/troubleshooting-ov

We may want to rework this section to include troubleshooting scenarios that are specific to Serverless (or at least include some examples that are not just core Security troubleshooting).


Original issue: https://github.com/elastic/docs-content/issues/81