[BUG] Security test failure of action validation feature

[bowenlan-amzn]

What is the bug?
During 2.4 release testing, the security tests failures are related to action validation feature introduced in this release.
Test failures: opensearch-project/opensearch-build#2649 (comment)

The bug in action validation feature breaks the existing ISM explain API when security enabled totally. If user calls explain API, a java.lang.IndexOutOfBoundsException: Index 0 out of bounds for length 0 exception shows up.

How can one reproduce the bug?
Reproduce by starting up a security enabled docker cluster, and run security enabled test against it.

Fix PR: #607

[bowenlan-amzn]

Close this as code fixes have been merged in main and 2.x branches.