[Actionable observability] Alerts page - Fix page goes blank with invalid query input

[maryam-saeidi]

📝 Summary

When an invalid input such as { is entered in query input, it will cause the page to goes into blank:

Screen-Recording-2022-10-19-at-1.51.15-PM.mp4

Another query to reproduce the error, suggested by @CoenWarmer here:

host.cpu.usage >= "25%"""

✅ Acceptance Criteria

• Fix the above-mentioned issue by making sure the input in the search bar is valid before attempting to get the related alerts from ES.

💡Implementation hint

@Kerry350 already found a way to fix this issue for the logs' search bar, this fix can be found in this PR

[elasticmachine]

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