Simplify getViewInAppRelativeUrl configuration

[maryam-saeidi]

📝 Summary

Currently, getViewInAppRelativeUrl is configured at the rule registration level (example). This logic is exactly the same for all the observability rules as shown below:

The current implementation in observability, as done in this PR, seems a bit repetitive and unnecessary, especially since there are few solutions to cover. Also, it will make rule creation harder by having more configurations.

✨ Improvement

Given the fact that we only have a limited number of apps with their own rule details page (Stack, Observability, Security), I was wondering if, instead of configuring this function for each rule separately, it would be possible to decide which rule details page to show based on an existing parameter in the rule.

📔 Side note

I noticed that in the security solution, they also include time while creating the rule details URL, so maybe we can have a default implementation for accessing the rule details page in each app and override it only if it is needed.

[elasticmachine]

Pinging @elastic/response-ops (Team:ResponseOps)