[BUG]: "Indexes" field in "Create threat detector" flow gives a wrong impression that user can use frontend index patterns as a source for threat detection.

[xeniatup]

What is the bug?
The "Indexes" field in "Create threat detector" flow gives a wrong impression that user can use frontend index patterns as a source for threat detection.
https://playground.opensearch.org/app/opensearch_security_analytics_dashboards#/create-detector

What is the expected behavior?
To clarify the meaning of the field, the field label should be Select or input source indexes or aliases, and the helper text underneath the input should clarify that user can enter * as a wildcard pattern to match multiple indexes as Use * as a wildcard pattern to match multiple sources.