[Actionable Observability] - Replace the global feature-flag for the Alert Details page with App-based feature flag

[fkanout]

📝 Summary

Part of #138645

In #139216 we introduced the global feature flag xpack.observability.unsafe.alertDetails.enabled so the user can access the new Alert Details page FOR ALL RULE TYPES

While working on the Alert Details page we realized that the roll-out will be by App. e.g. We are targeting APM rule types first. In that case, providing a global feature flag is no more suitable for a roll-out by App.

✅ AC

• Remove the global feature flag xpack.observability.unsafe.alertDetail.enabled
• Instead, provide 4 feature flags:
  • xpack.observability.unsafe.alertDetails.apm.enabled
  • xpack.observability.unsafe.alertDetails.infra.enabled
  • xpack.observability.unsafe.alertDetails.logs.enabled
  • xpack.observability.unsafe.alertDetails.uptime.enabled
• Creating a mapping between the rule type and the feature flag to decide whether to show the Alert flyout OR the Alert Details age

[elasticmachine]

Pinging @elastic/actionable-observability (Team: Actionable Observability)