Related #1387#1387

We want to improve the filtering experience in the alert rules. In the case of the Latency threshold rule, we are supporting only transaction metrics in the KQL filter (The transaction metrics can be found here: https://www.elastic.co/guide/en/observability/current/apm-data-model-metrics.html#_transaction_metrics) So filtering by other fields won't work but the autocomplete is suggesting the fields.
The result is that when a field that is not supported is selected with an autocomplete option the chart won't load:

Some ideas I have:

• We can add a message (in a tooltip for example) next to the field that we are supporting only transaction metrics. This is probably the easier fix
• Limit the KQL autocomplete suggestion to the supported metrics: