Closes elastic#217007

## Summary

This PR updates the logic in the getCasesTitle function to better
control and format the generated case title, ensuring it compiles with
the length limits.

The case title is formed by concatenating:  `Rule name` + `suffix`
The `suffix` is structured as: ` - Grouping by` + `grouping description`
+ `(counter)` + `(Auto-created)`
The problem occurs when a rule with a very long name is created, a cases
action is added to that rule and the group by alert field is
**rule.name**. In this scenario, the rule name and the grouping
description become very long and if the case title exceeds the
160-character limit, the case won't be created.

What changed:
- `Rule name truncation`:
- the **rule name** is now trimmed to a maximum of **100**
**characters** (including `...` if needed)
- `Suffix restructuring`:
    - the total **suffix** length is limited to **60 characters**
- the **grouping description** is dynamically trimmed (with `...`) to
ensure the suffix doesn't exceed the limit

(cherry picked from commit 6d95b2a)